He's still quite present on the show itself.
The massive spike of applause and cheers in Pop Culture J! ep 1 when Colin mentioned that Johnny was announcing the show sounded very legitimate, and appeared to catch Colin a tiny bit by surprise (but delighted). He also for the same episode had a delightful and hilarious category, Johnny Gilbert: Film Thespian, where he voiced an entire category of deliberately hammy and over the top line reads from movies, and it was magnificent.
Even if he's no longer always present in the studio itself, Johnny Gilbert is just as if not more of a part of the show than he's ever been. There aren't very many folks from the classic era of the genre left, but he's still going
strong at 96 and I plan to cherish and be grateful for every episode we still have with him.