I think the issue of multiple engagements have been taken care of as Manchester city have been eliminated from the EFL cup and are now left with the champions League, the premiership and the FA cup to contend with for now, but for the problems rocking the team, am sure Pep Guardiola would figure out something because this particular situation is not new to him though not at this dimension but am sure he is up to the task based on his level of professionalism and years of experience in coaching roles across different clubs.
This is just one of the numerous challenges faced by managers during their professional careers. Although Pep is not still doing bad, at least not as bad as Ancelotti of Real Madrid so far. He's still holding the team all the way up and has performed well to remain second on the table standing just behind the Liverpool club.
The manager knows how to play his cards well but I think he might also require to bring in more younger talents to play other less important competitions they're faced with so that a very strategic and professional player doesn't go to injury in a little match when the team still got bigger games to play.