Yes, it does require extensive changes to the way developers write controllers.
Are you able to roll out jQuery in parallel with your current Mojo applications? it'll open up the doors to building a proxy layer and then controllers can be slowly moved over from Dojo to Mojo bit by bit...
To answer the big question on Mojo's roadmap, we're all here to answer questions on the existing framework but any further development has ceased for a while now.
Cheers,
Jaime