There's been whispers about Feinstein for a while now. Here's a recent article on this subject: https://www.foxnews.com/politics/dia...tebook-pergram

Biden's is markedly slower in the cognitive department but still functioning.
Pelosi's lost a couple of steps but she's still doing OK.

I haven't seen any other elder politicians speaking publicly. Those that have issues tend to be shielded from the public by their aides. I haven't seen any clips of Feinstein speaking so I can't personally comment on how she's doing cognitively.

But you're asking the rule makers to put themselves out to pasture. It's more likely for them to die in office. Chuck Grassley, at 88, is running for reelection this midterm - and he's almost guaranteed to be reelected. Feinstein's up for reelection in 2024.