I don't think anyone will accept to take the job at this point of the season. If they will end to sack Pirlo the team will probably go to Tudor who is the coach in second.
For the next season if Pirlo goes I think the most probable is Allegri Bis.
Let's see though. We might speculate about a change at the end of the season and then it ends up not happening. Juve's management might not end up showing Pirlo the door. Either way, we have to wait till the end of the season to find out. Allegri is a fantastic choice though (if he still has it in him). His first spell at Juve was super impressive and it would be good to see him on Juve's bench managing the team. Pirlo isn't completely ruled out yet but time will tell.