@MontereyJack,
Ideally if that happens President Trump will refuse to concede and instead insist on endless recounts and legal challenges. If those fail, he should still refuse to concede (though he should quietly leave office at the appointed time).
The reason for this is not for any great strategy, but just to show progressives the disrespect that they deserve.
More importantly, President Trump should appoint a range of independent prosecutors to endlessly hound the Biden Administration with criminal investigations.
The reason for this is to do as much damage as possible to the Biden Administration and prevent them from achieving their goals. Bonus points if the legal stress splits up any marriages or if some progressives are sent to prison.
When the Republicans later retake Congress, these criminal investigations can then be used as the basis for impeachment.