MPS on Java 9?

It will depend on the IDEA platform. MPS is in-synch with IDEA platform at this moment, and they will use the same runtime JDK as they do.

Unfortunately, it does not (filed at https://youtrack.jetbrains.com/issue/MPS-27133):

c:\Users\Niko\MPS 2017.3\bin>mps.bat
Java HotSpot(TM) 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
Java HotSpot(TM) 64-Bit Server VM warning: Ignoring option MaxPermSize; support was removed in 8.0
log4j:WARN No appenders could be found for logger (jetbrains.mps.util.ClassPathReader).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.intellij.ide.ClassUtilCore to field sun.net.www.protocol.jar.JarFileFactory.fileCache
WARNING: Please consider reporting this to the maintainers of com.intellij.ide.ClassUtilCore
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
[ 0] INFO - #com.intellij.idea.Main - ------------------------------------------------------ IDE STARTED ------------------------------------------------------
[ 13] INFO - #com.intellij.idea.Main - IDE: JetBrains MPS (build #MPS-173.1427, 05 Dec 2017 01:32)
[ 13] INFO - #com.intellij.idea.Main - OS: Windows 10 (10.0, amd64)
[ 14] INFO - #com.intellij.idea.Main - JRE: 9.0.1+11 (Oracle Corporation)
[ 14] INFO - #com.intellij.idea.Main - JVM: 9.0.1+11 (Java HotSpot(TM) 64-Bit Server VM)
[ 15] INFO - #com.intellij.idea.Main - JVM Args: -XX:MaxJavaStackTraceDepth=1 -XX:-OmitStackTraceInFastThrow -Djava.net.preferIPv4Stack=true -Dsun.io.useCanonCaches=false -XX:SoftRefLRUPolicyMSPerMB=50 -XX:+UseConcMarkSweepGC -Dintellij.config.imported.in.current.session=true -Dide.mac.message.dialogs.as.sheets=false -Dapple.awt.graphics.UseQuartz=true -Dfile.encoding=UTF-8 -Xss1024k -ea -Xmx950m -XX:MaxPermSize=256m -XX:NewSize=256m -XX:+HeapDumpOnOutOfMemoryError -Xverify:none -Djb.vmOptionsFile=c:\Users\Niko\MPS 2017.3\bin\\mps.exe.vmoptions -XX:ErrorFile=C:\Users\Niko\java_error_in_IDEA_%p.log -XX:HeapDumpPath=C:\Users\Niko\java_error_in_IDEA.hprof -Xbootclasspath/a:c:\Users\Niko\MPS 2017.3\bin\\../lib/boot.jar -Didea.paths.selector=MPS2017.3 -Didea.platform.prefix=Idea -Didea.jre.check=true -Didea.main.class.name=jetbrains.mps.Launcher
[ 18] INFO - #com.intellij.idea.Main - ForkJoinPool.commonPool: java.util.concurrent.ForkJoinPool@5ab81eee[Running, parallelism = 3, size = 0, active = 0, running = 0, steals = 0, tasks = 0, submissions = 0]
[ 18] INFO - #com.intellij.idea.Main - JNU charset: Cp1252
[ 71] INFO - #com.intellij.idea.Main - JNA library (64-bit) loaded in 52 ms
[ 76] INFO - penapi.util.io.win32.IdeaWin32 - Native filesystem for Windows is operational
[ 1688] INFO - llij.ide.plugins.PluginManager - 28 plugins initialized in 460 ms
[ 1702] INFO - llij.ide.plugins.PluginManager - Loaded bundled plugins: CVS Integration (11), Debugger API for MPS (173.1427), Execution Api and Utility Languages (173.1427), Execution Configurations (173.1427), Execution Languages (173.1427), Git Integration (8.1), HTTP Support Plugin (173.1427), IDEA CORE (173.1427), Idea Integration for MPS (173.1427), Java Debugger for MPS (173.1427), Jetpad (173.1427), Languages DevKit (173.1427), MPS Build languages (2017.3), MPS Console (173.1427), MPS Context Actions Tool (173.1427), MPS Core (173.1427), MPS Diagram Editor (173.1427), MPS Java Integration IDE (173.1427), MPS Testing (2017.3), MPS samples (173.1427), Make (173.1427), Migration 2017.3 (2017.3), Migration Support (173.1427), Model Checker (173.1427), Subversion Integration (1.1), Terminal (0.1), Trove Collections language for MPS (2017.3), VCS Integration for MPS (173.1427)
[ 1956] INFO - ellij.util.io.PagedFileStorage - lower=100; upper=500; buffer=10; max=898
[ 1993] INFO - pl.local.NativeFileWatcherImpl - Starting file watcher: C:\Users\Niko\MPS 2017.3\bin\fsnotifier64.exe
[ 2016] INFO - pl.local.NativeFileWatcherImpl - Native file watcher is operational.
[ 2577] INFO - .history.utils.LocalHistoryLog - local history version mismatch (was: 0, expected: 6), rebuilding...
[ 2577] INFO - .history.utils.LocalHistoryLog - FS has been rebuild, rebuilding local history...
[ 2884] INFO - til.net.ssl.CertificateManager - Default SSL context initialized
[ 2943] INFO - gs.impl.UpdateCheckerComponent - channel: release
[ 3065] INFO - il.indexing.FileBasedIndexImpl - Index exts enumerated:79
[ 3070] INFO - il.indexing.FileBasedIndexImpl - Index scheduled:4
[ 3072] INFO - tellij.psi.stubs.StubIndexImpl - All stub exts enumerated:0
[ 3074] INFO - tellij.psi.stubs.StubIndexImpl - stub exts update scheduled:1
[ 3123] ERROR - llij.ide.plugins.PluginManager - com.intellij.ide.plugins.PluginManager$StartupAbortedException: Fatal error initializing 'jetbrains.mps.ide.diagnostic.MPSErrorReporterConfigurable'
java.lang.RuntimeException: com.intellij.ide.plugins.PluginManager$StartupAbortedException: Fatal error initializing 'jetbrains.mps.ide.diagnostic.MPSErrorReporterConfigurable'
at com.intellij.idea.IdeaApplication.run(IdeaApplication.java:210)
Caused by: com.intellij.ide.plugins.PluginManager$StartupAbortedException: Fatal error initializing 'jetbrains.mps.ide.diagnostic.MPSErrorReporterConfigurable'
at com.intellij.ide.plugins.PluginManager.handleComponentError(PluginManager.java:274)
Caused by: java.lang.NoClassDefFoundError: javax/xml/bind/DatatypeConverter
at com.intellij.credentialStore.kdbx.KdbxKt.<clinit>(kdbx.kt:164)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.DatatypeConverter
at com.intellij.util.lang.UrlClassLoader.findClass(UrlClassLoader.java:222)
[ 3127] ERROR - llij.ide.plugins.PluginManager - JetBrains MPS 2017.3 Build #MPS-173.1427
[ 3129] ERROR - llij.ide.plugins.PluginManager - JDK: 9.0.1
[ 3130] ERROR - llij.ide.plugins.PluginManager - VM: Java HotSpot(TM) 64-Bit Server VM
[ 3130] ERROR - llij.ide.plugins.PluginManager - Vendor: Oracle Corporation
[ 3131] ERROR - llij.ide.plugins.PluginManager - OS: Windows 10

Start Failed: Internal error. Please report to http://jb.gg/ide/critical-startup-errors

java.lang.RuntimeException: com.intellij.ide.plugins.PluginManager$StartupAbortedException: Fatal error initializing 'jetbrains.mps.ide.diagnostic.MPSErrorReporterConfigurable'
at com.intellij.idea.IdeaApplication.run(IdeaApplication.java:210)
Caused by: com.intellij.ide.plugins.PluginManager$StartupAbortedException: Fatal error initializing 'jetbrains.mps.ide.diagnostic.MPSErrorReporterConfigurable'
at com.intellij.ide.plugins.PluginManager.handleComponentError(PluginManager.java:274)
Caused by: java.lang.NoClassDefFoundError: javax/xml/bind/DatatypeConverter
at com.intellij.credentialStore.kdbx.KdbxKt.<clinit>(kdbx.kt:164)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.DatatypeConverter
at com.intellij.util.lang.UrlClassLoader.findClass(UrlClassLoader.java:222)

[ 3510] INFO - .openapi.application.Preloader - Finished preloading com.intellij.openapi.actionSystem.impl.ActionPreloader@716e6a3
[ 3560] INFO - .openapi.application.Preloader - Finished preloading com.intellij.ide.ui.search.SearchableOptionPreloader@292308ab
[ 19063] INFO - il.indexing.FileBasedIndexImpl - START INDEX SHUTDOWN
[ 19063] INFO - #com.intellij.idea.Main - ------------------------------------------------------ IDE SHUTDOWN ------------------------------------------------------
[ 19107] INFO - il.indexing.FileBasedIndexImpl - END INDEX SHUTDOWN
[ 19107] INFO - stubs.SerializationManagerImpl - START StubSerializationManager SHUTDOWN
[ 19109] INFO - stubs.SerializationManagerImpl - END StubSerializationManager SHUTDOWN
[ 19123] INFO - newvfs.persistent.PersistentFS - VFS dispose started
[ 19143] INFO - newvfs.persistent.PersistentFS - VFS dispose completed