Wouldn’t Pence appoint another Vice President, so even if the rats 🐀 were able to get rid of both Trump and Pence, the evil wench in the House, still won’t be the president.
When VicePresident Agnew resigned, some Democrats (notably John Conyers of Michigan) tried to block the approval of a new VicePresident so that the Democrat Speaker of the House would be first in line for Presidential succession. Had that occurred, the Democrat Carl Albert would have become President when President Nixon resigned.