"A president who spent months catering to the Republican conservative wing now appears unbound by ideology and untethered by party allegiances."
At which point the GOP has absolutely no reason to support/protect Donald and would much prefer a more stable lapdog like Pence.
If possible, they could elevate Ryan to VP (continuing his career arc of failing upward), which avoids yet another Tea Party ouster and clears space for whatever Alex Jones clone they want to install as Speaker.

Of course, this scenario assumes that Pence survives whatever shenanigans take down Donald, which is not a given.