Sony need to sit down and plan ahead as a whole unit. I want PS to communicate and integrate features with their TV division/camera/mobile etc. Sony have a huge fanbase to sell game oriented tv's to.The first-party output will be higher for sure, because they have added new teams.
ND released 3 games last gen (Uncharted 4, Uncharted Lost Legacy, TLOU2, in addition to TLOU remaster).
SSM had one game cancelled and the studio was being restructured, hence they could only produce 1 game, but now they have two teams, and the GOW trilogy all planned out. I am confident we will get 4 games from them this generation (3 for sure).
SP's 2 games sound about right. GG also has 2 teams and 400 people now (including an xDev team). I'm expecting at least 3-4 games from them this generation. And Insomniac, as you said, is a beast. They are the dark horse of this generation and will play a crucial role for Sony, especially with PSVR2 (I have a hunch they are working on a PSVR2 game).
I think Sony will be fine in terms of first-party output. They have already released 5 PlayStation Studios game in the first 6 months of launch, with 2 are lined up for the next 3 months. This is fantastic output.
Now all eyes are on Sony if they purchase a big publisher and take that content off Xbox (ala Bethesda). But Sony does not operate that way. So shouldn't be judged based of their inaction on that front, imo.
All their top studios need to expand and hire the best talent but also reduce crunch and loss of talent(Naughty Dog). PD needs an overhaul and to be streamlined. Maybe an European branch?
Acquisitions need to be made but sensible ones.
SE is a good bet to buy outright along with Kudokawa.
Also Sony will be crunching the numbers for gamepass and will be working on a competitor mark my words. They just don't need to rush in. Take your time get the balance right.