We can speculate that it's recently gone into production, because SimGuruGrant got moved to a new Sims project and is no longer on Sims 4. But that was a pretty recent change, and it takes a few years to make a game, and with everyone having to work from home b/c of the pandemic, that's probably going to slow down the production even more.
We've had a leak from a shareholder that they're thinking of adding online gameplay to Sims 5. That's really all we know so far. EA was just sharing some info. to their investors to get funding for the game's development. We weren't supposed to know about that. So my guess is that it's still in early stages of development. It's going to be quite a while before it's actually announced.
Also, I would assume they will wait for PS5 to come out, and for whatever the next gen of xbox is going to be, before releasing the game. They'll probably release it on all platforms from the get go, since they worked so hard to get Sims 4 console players caught up to PC releases.