That's not how it works. Each developer is a resource. The ones that are working on a patch can be alocated to work on the expansion and they end up doing it regardless, as we can see with the latest patch, they are only developed after the expansion comes out. This is fairly obvious as last patches tend to last nearly a year. They do put the whole team to work when they are about to launch an expansion. If they did they would've had this next patch ready to launch before they had to move to working from home.
As for pleasing shareholders or players, it's a finer line to cross.
What will shareholders and execs be ok with as far as a delay goes? What kind of a delay are we talking about? Delaying would also desynch the release of WoW expansions on the fall, which tends to be the time of the year that sees more sales.
Players, what kind of delay are we talking about? Players are already upset with the current delay, so i don't know.
My personal opinion is that they should indeed cut the patch IF indeed it means the next xpac will come out in the regular cadence.
If we are looking at a 5-6month delay like FFXIV, i think that rivers will flow with bile.
Honestly, i think FF is gonna hurt too, but the team on that game communicates a lot better and listens to the fans, so that earned them goodwill.
With all this said, given the delay of Blizzcon this year, it's a given that all projects are already delayed and they are gonna go with that. AKA, for better or worse it sounds like SL might become the longest WoW expansion ever, barring drastic measures.