I'm late to this thread and replying via a mail-to link from the archives, for both I apologize.
I wanted to express my support for this proposal. I'm pleased that it addresses the specific concerns that I and others raised in the discussion of final/sealed-by-default regarding the need for some sort of escape hatch to work around framework bugs. Keying patches to specific framework or OS revisions seems like a reasonable approach. I brought the idea up at Seattle Xcoders this week and there was general agreement that folks were happy to update their apps for updated framework versions, whether to remove no longer necessary patches or to specify that some patches were still needed.
There are lots of interesting corner cases, of course, to deal with customers who update their OS but don't update an app and vice versa, but lifting patches to the language level seems like a promising way to improve robustness while decreasing the burden on framework authors of dragging "do not break" apps along.
Thanks again for the proposal.
Curt Clifton, PhD
The Omni Group