I don’t know where you are getting your information but Apple is absolutely dropping OpenGL from the MacOS and requiring developers to use the Metal framework instead. This is old news at this point.
I think it’s way too soon to assume the end of 32bit support is going to eliminate limitations or produce some massive shift in the game’s capabilities. We don’t know that, and frankly I don’t think it’s reasonable to jump the gun and assume it will. The under the hood changes happened in 2015, the game has been 64bit since then but they did nothing with that until C&D in 2017. Let’s remain realistic here Jack.
Personally I think the game is reaching a point where the studio is having a lot of problems maintaining it. Clearly they are contracted to keep building it, but performance and quality are steadily on the decline, bugs aren’t being fixed, and content is not coming out nearly at the rate it was even a few years ago. Why drop 32bit? Well it means the studio will have to do less optimization, and they won’t have to worry about everything they add on top of each other crashing the game by trying to use 4GB or more of memory. Anyone expecting this to somehow molt Sims 4 into a new game, or a different game, you will be disappointed.
