If they really are trying to push him out, I think it's a concession at this point and they're going to focus on trying to build better optics so the eventual candidate comes out losing gracefully. Whether that means Pence or another candidate is running in Trump's place, they'll probably try to change their tone to use a lot of words like 'unity' and such. Even knowing they likely wouldn't win with Trump dumped, it would become more about PR at this point so the GOP can try to avoid going down in history as a party of divisive rhetoric. Not that the PR efforts would work, but I think they'd be trying to rehabilitate the party to be in a better spot for 2024. The chances of Trump winning are fairly low and I don't see a replacemtn candidate doing any better (possibly would do worse), so the whole thing seems like an attempt to concede early so the party loses with grace, mirroring McCain's handling of the final days of the 2008 election. He knew he was losing and I remember his tone changed quite a bit once Obama soared ahead in the polls, casting himself as a graceful, honorable lost cause candidate, and basically giving zero fucks that Palin was running around screaming conspiracy theories, since by then the damage was already mostly done.
On the other hand, I wonder if this is just an elaborate, desperate stunt to make Biden and his supporters drop their guard and run a lackluster campaign. We saw how badly it went for Clinton when she and her team took for granted they would win. Then I can imagine Trump going to rallies in the days leading up to it boasting about how "everyone wrote me off, even my own party, they said I was dropping out, but here I am still fighting. Rarr fake news establishment rarrr more noise and grumbling rarrr". Trump seems to love portraying himself as the me-against-the-world underdog and it could all be a desperate attempt to cast himself as such in the eyes of voters.
For that matter, it seems more like speculation than anything else coming from GOP insiders. But I can't help feeling like this is all just another PR stunt for Trump, perhaps hoping a wave of supporters will flood him with adoration and requests to keep running. Guy seems to crave validation.
Or maybe he is genuinely afraid of prosecution and this is last ditch effort, hoping Pence will then be elected so he can subsequently be pardoned.