People are also trading
The base rate for any votes of representatives who are also members of the President's party being for impeachment is 50 % - this happened with Bill Clinton, Donald Trump #2, but not with Donald Trump #1 or Andrew Johnson.
On the other hand, it was never introduced by a member of the President's party (if Nixon went through, 20 %), and barring party switches or deaths, the GOP is guaranteed hold a majority in the 118th House in 2026. This is relevant because I do not see much possibility it's even attempted without bipartisan support.
Anything higher than 30 % is very unrealistic. I can only imagine this if Trump is convicted for a serious crime, which is nigh impossible in the Epstein situation. Or something Nixon-like.
However, I would say at least 5 % is legit. Especially with eg. Trump turning on MTG.