I am pretty much sure that the answer is "no", but still got some hope.
Say I have a simple LL(1) language to implement. MPS is great at providing an editor and a compiler for my language. But what if I have some code in that language written outside MPS, represented in raw text files? Will it be possible to import that files into MPS?
I saw that you have added in MPS 2.0 support for that feature if the DSL a superset of Java. What about arbitrary languages, not Java-like?