Not your screen monkey (he/him)
You increase staff in the lead up to a new edition, you don't reduce it.
Generally, I'd say so. There were substantial layoffs shortly after major releases including 3.0 and 4 (the one that included Jonathan Tweet). On the other hand, Skip Williams was released by WotC in 2002 - shortly before the 3.5 release.
I wouldn't be surprised to see WotC use the savings in cutting long-time employees, each of whom probably makes at least twice what a starting employee would make, to pay for an increase in staff numbers. Perhaps in preparation for a new edition...?