I reckon they'd finally have to get R working natively on the new chip. I don't foresee Apple offering the fat binary support in the long term. It's probably only an intermediate solution for the transitional period. Also, does it mean the native version of R will finally work on the iPad? I know Apple doesn't allow compilers but there are a few examples like Pythonista and Apple's own Swift playground. It'd be cool to get R Studio on the iPad.
Just to be clear, PPC-Intel fat/universal binaries are still supported even on Big Sur, the PPC portion is just ignored. I don't expect Intel-Arm binaries to go away any time soon.
I believe what you're really thinking of is Rosetta though. That, indeed, is sadly unlikely to be around forever. We have history as an indication of that.
When Apple transitioned from PowerPC to Intel the fat binary support (Rosetta) lasted 3 OS updates or about 3 years. Definitely won't be a super long term thing, but there's plenty of time I guess.
