I miss the dream team too but the decisions that have led to these departures have been in the works long before Jim.
The writing was on the wall when Sony decided to consolidate SCEA/SCEE/SCEJ into a global office in San Mateo. From what I know on the business side, this is not and has not been a totally smooth process, but the long term vision is that they will have more streamlined operations, resources, marketing, etc. for studios to take advantage of. Closing Japan Studios was a business move and shouldn’t be surprising to anyone who manages teams/budgets. When your console claims to fame over a decade are Bloodborne (outsourced), Demons souls remake (outsourced), shadow of the colossus remake (outsourced), Last Guardian (10+ year development), and *checks notes* Knack, there’s not much reason to keep the gang around aside from nostalgia.