ManC will fight Spurs twice at UCL and EPL This week, both teams must continue to focus on both competitions. and I'm sure ManC and Spurs really want a win from both competition. after those match ManC had been waiting for the manchester Derby (EPL). if in those three matches ManC failed to pick full points I am sure they will fail in both UCL and EPL competitions.
I think they cannot do the quadruple and agree with you. They will have to sacrifice something. If they get knocked out of Champions League this week, then sure, FA Cup and Premier League is theirs, they have a full squad. But believe me, if they reach the semifinals, they will probably meet Juventus so they will do everything they can to progress to their first ever final, and this knowing Pep might cause them to wobble in EPL.
But if they want to pick up max points and win EPL, they will sacrifice CL. Not because they want to, but because they can't do it.