Rosetta will be on its last legs anyway when this ships. Also, the A* Series might not have the hardware emulation silicon optimizations for Rosetta 2. I could see it go either way.
A12Z DTK in 2020 already ran circles around PCs using Rosetta. There's no reason why A18/A19 can't.
There's no chance it won't support Rosetta. Apple is selling its strengths here; zero reason to deliberately cripple features.