While I agree that Taylor is very weak when it comes to making changes and he seemingly doesn't have the capacity to manage a squad outside of narrow band of about 14 players, I'm not worried about a raft of important players leaving. One thing that has gone extremely well under Nils Nielsen coming in is we've seen Keating, Greenwood, Shaw, Hemp and Hasegawa commit to long term contracts. Plus Roord is only one year into hers and (i think?) Park too. I'm not concerned about this side being broken up.
Amongst the players that have left this time around are two players retiring and our third choice goalie. Morgan had become a fringe player (wrongly IMO) and Mace wasn't breaking in either.
The only big name i think we could lose is Kelly but i think that's as much about her wanting to try somewhere new and also she wasn't great second half of last season. Aleixandri will probably leave eventually but only in the same way any decent Catalan player ends up back at Barcelona in the end.
Whatever happens, I think the signings we make will be upgrades. Seeing Dom Janssen, Viv Miedema and Risa Shimisu all being linked at the mo who would all be stellar signings.
Ultimately though, I do think we will need to upgrade manager sooner rather than later and it will need to be someone absolutely top drawer to compete with Chelsea. Like you say, Bompastor is a real statement of intent. You can't get away with just putting a company yes-man in charge these days if you want to seriously challenge. Nils has brought a sense of elite professionalism to the club and we'll need to see that reflected in our choice of coach in the not too distant future.