Does this mean that this new 4.1 RC1 is stable/mature enough (still in the incubating phase or not)?
The 4.1 RC1 is still in incubating. It means that there is no production support on this version.
What about the new Equinox support? Can I expect my bundles to seamlessly run on Equinox (as they did on Felix)?
Yes, the 4.1 RC1 uses Equinox as default. If you would like, you could configure the ESB to use Felix as before.
And finally: what is the roadmap and when can we expect the final release?
We are still working through our plan for final release. You will hear announcement soon. BTW, You can expect the final release in the first quarter of this year.