I'd be a no on the Alonso / Casas deal as well. Just like I'd be a "no" on Duran for Soto. In both instances, I firmly agree that Alonso is better than Casas and that Soto is much better than Duran, but there you're talking about a two very good young players with 6 seasons of control each (counting this one) for two outstanding players but each of them only have 2 seasons of control left, and I cannot picture the Sox spending what would be required to extend them.
Scherzer isn't / wasn't a rental. The Rangers required that he pick up his option (so he's in Texas this season and next) in order to move LA Acuna. (
https://www.mlb.com/news/whats-next-after-max-scherzer-trade-to-rangers#:~:text=The Rangers will pay Scherzer,$36 million of the deal.)
I sincerely hope so, but I really doubt it.
At this point I'd be pretty happy with adding the functional equivalent of Paul DeJong and Mike Lorenzen (as in a likely more competent MI and something that is a starting pitcher), if nothing else to convince the team to keep playing until reinforcements arrive / if they don't (Sale, Whitlock).
Though I'm beginning to think it's more and more likely that there aren't really any additions of even the above caliber that will be made. Which if they are not, I'd pivot to selling because I think not adding would crush morale as much as selling would.