It's sad, but sadly people gets old and at some time has to retire (he's 60 years old).
I wish him the best, we got a lot of fun with many games thanks to him.
No.
As head of PlayStation Indies, while scouting indies Yoshida found Stellar Blade and forwarded it to Hermen/PS Studios. Hermen, head of PS Studios, signed it as a 2nd party game. Hermen is the one in charge of 1st & 2nd party games like Sterllar Blade, Yoshida is in charge of supporting 3rd party indies instead.
Sony started to work with Concord in 2018, when Shuhei Yoshida (not Hermen) was the head of PS Studios. Yoshida was the one who greenlighted Concord, not Hermen (who became head of PS Studios in November 2019).