A key problem facing the Demicrats is will they follow Trump’s plan in regards to the vaccines. According to his plan by May 70% of the US will be vaccinated, giving the US herd immunity allowing the US economy to reopen. Democrats may have a slower approach in administratingthese vaccines.
Another problem is gridlock and or government shutdown.
As far as prosecuting Trump, he already was impeached and there was no smoking gun why do you think these other charges will be substaniated. If Biden is successful Trump will fade away but if he is prosecuted he wil have free publicty.