An assassination attempt, much less success by a left-wing radical will not end with Biden in the White House. It would be an immediate Civil War, Do Not Pass Go and Collect 200 Dollars scenario. If the attempt fails, and Trump survives, you can expect him to immediately activate the Insurrection Act and as succinctly pointed out:
Let slip the dogs of war, indeed, the bloodshed would be immediate and brutal. Imagine, if you will, 70+ million patriots, plus a sizable portion of the police and military being ordered directly to kill or capture every Democrat power broker and rabble rouser. The very agents that Governors and Senators rely on for their protection would immediately arrest or execute them. Government buildings would be overrun, politicians hung, shot or defenstrated. Community militias would roadblock major highways and gun down interlopers and government agents alike. Colleges and corporations would be stormed, and many agents of communist anti-Americanism executed by make-shift home grown Einsatzgruppen. The Democrat stronghold cities would burn.
If the attempt succeeds, well....
None of these scenarios end with Biden taking power, because with the current situation where a healthy majority of Americans see the election as fraudulent, the situation can only intensify the violence and aggression of the right-wing. Any Democrat taking power after stealing the election and killing Trump will be seen as an unacceptable loss, and all high ranking Democrats will be priority targets for revenge killing at all levels from organization to lone wolves. Even in places where Democrats were legitimately elected, if such places exist, will be targeted as any Democrat in office will be suspected of illegitimacy.
The only hope of Biden/Kamala surviving after Trump is killed would be to immediately flee the USA and go into high security protective custody with an allied nation, and even then they might get drone striked by an official order or by a particularly based drone pilot.
