I don't think Sony needs to go to town if MS acquires ABK. Acquiring thousands of employees can create a negative ripple effect on quality. It can also lead to increased expenses and a potentially negative ROI.
I think more strategic moves would be preferred by Sony. For example, acquiring Capcom. They are leaner, have multiplatform IPs like Resident Evil, DMC, Monster Hunter that, if taken off from Xbox, will help Sony. And Sony already has SquareEnix games exclusive, so buying them wouldn't really matter in this context.
Most of all, I think Sony will have to make one nuclear move: make GTA 6 a full PS5/PC exclusive. If Xbox Series X|S is without GTA throughout this generation, it would nullify any impact ABK might have had. And it'd have a huge impact on next-gen console sales as well, as some Xbox fans might buy a PS6, thinking what if GTA 7 doesn't release on Xbox again.
That's all Sony needs in my opinion.
P.S. Before everybody starts attacking me, I'm against this kind of stuff. That's why my hope is that the MS/ABK acquisition falls through, and Sony doesn't feel the need to do stuff like this. And all multiplatform games continue to release on all consoles, creating equal opportunities for both companies, consoles, and their userbase.