While I'm not sure how true this might be, there has been speculation about both being in production as far back as last year. This "insider" claims that it is true.
I can corroborate that a new Sly Cooper and a new Infamous are in development. https://t.co/ymgwhJyJW3— AccountNGT (@accngt) March 2, 2022
There are also rumors about a sequel to Ghost of Tsushima being in production. I have my doubts that Sucker Punch will be an active role in all 3 games (especially considering Sly 4 was made by Sanzaru Games). If I had to guess, they'll outsource it to someone like Sumo Digital as they did for LittleBigPlanet 3 and Sackboy's Big Adventure. I could also see the Infamous title being a remaster/remake of the first 2 games to release as a bundle from Bluepoint Games.
This is just speculation on my behalf. What do you guys think? Could Sucker Punch manage to juggle 3 games? If not, what do you hope they are working on and who would make the other games?