FreddyFox1234 Yes, Rosetta is the translation layer that makes Sims 3 run on ARM Macs at all. So no Rosetta means no Sims 3, at least not in its current form.
There are a few reasons not to worry about this though. One is that Apple won't be removing Rosetta from existing OSs, so you could simply not update to whichever build no longer included Rosetta. The previous OS should be compatible with almost any other app you'd want to run for at least a couple years, if current patterns hold. And by the time you actually had to update, would you be ready for a new Mac? Unless you only recently bought your current one, it might be time to upgrade in 2029-2030 when you really did need to be on the new OS, and you could keep your old Mac around for Sims 3.
There is also the possibility of running Windows on your Mac, either through Parallels or possibly through Bootcamp if that comes back. ARM Macs cannot be Bootcamped at the moment, but the original reason for that—Microsoft had an exclusive contract with someone else for Windows on ARM—is gone. And while the Windows ARM-to-x86 translation layer isn't as good as Rosetta, it's serviceable and still getting better.
The other reason is that it's still possible EA will update Sims 3, or release some kind of compilation as was done for Sims 1 and 2. I do realize these were only released for Windows, but Sims 2 at least has a compatible Mac version, and Aspyr still holds the license to sell it. Two years, or realistically four years before you have to make a decision, is a long time, and this is already-popular content that would take much less work than a full new game to bring to market.