I do think, unfortunately, that you are probably correct and that Apple will probably drop Rosetta 2 fairly soon after they transition the last new Macs to Intel. That will be a shame however. Apple has developed something so damn good they should just leave it in there effectively forever, just for the sake of backwards compatibility.
The only 'downside' is that some developers may not feel inclined to update their apps as promptly; but having a larger software catalog that works well is in all other ways a benefit to Apple and to Apple users.
Backwards compatibility isn't what Apple is known for... you're thinking Windows... which has a long history of being backwards compatible.
32 bit games won't even run on their latest INTEL OS... and haven't since Mojave. Rosetta 2 cannot be supported for all perpetuity because the hooks that allow them to do so are going away. In other words, the version of ARM that is running on your M1 now is not going to be the version that runs on it in the future. The same reason the original Rosetta went away is the same reason this one will too.
Out with the old... in with the new.
Since Apple has never been known for gaming... and people don't buy Macs for gaming... the notion that somehow now, in 2020 that will all change because of M1 is a fallacy. Reality is the preponderance of developers develop solely for Windows... DirectX to be exact. Their thought is this... you want to play their games, you come to the platform that has been running them for eons. The only reason you have been able to play any Windows games at all is because of bootcamp. In a nutshell, you went to their house. They have zero incentive to come to your house.
Is Apple buying game companies? No. Is Microsoft? Yes. And with Mircrosoft, it's purely to support their Xbox because they know they have no problem holding onto the gaming companies who develop for PC... the console market is an entirely different story.
You need to see some commitment for developing the games you like on the platform you use. I can assure you, that commitment isn't there. There is no incentive to support a company that has closed architecture over a company that supports open architecture.
Think about it... the billions of dollars each year going into to nothing more than GPU cards each year. You think game companies aren't getting some sort of kick back for supporting an industry that revolves around swapping GPUs every 6 months? If Apple were the top dog in gaming... there would be no GPUs to be bought because they would all be part of a closed eco-system. An entire industry would cease to exist. This is why Windows remains king of that hill. It is why it will ALWAYS remain king of that hill.