I think Trump could select a new nominee for AG who would serve until the end of the congressional session or until confirmed by the senate. That, however, is not a great solution either. An ‘unconfirmed’ AG would be viewed as a Trump-creature by the Media and would be portrayed as such. He/She might be plagued by threatened resignations by deputies every step of the way.
Any selectee would have to be recess-appointed and McConnell and Senate are not allowing any recess appointees since Obama tried to get Garland recess appointed to fill Scalia’s seat.
McConnell allowed Gorsuch and allows other judges to be confirmed using Reid’s ‘nuclear’ precedent in which Reid disallowed a call of 60 votes for cloture opting for a simple majority vote. This buried the filibuster for judicial nominee confirmations.
McConnell could go nuclear on administration appointees but that would be precedent-setting and McConnell is the typical DC bureaucrat not to make waves.
It’s a total suck situation.