We don't know if it's an Astro game, but it's likekly because we know they are working on a 3D action platformer with humor that will be bigger than the Astro games. In addition to be developing this game they alre also working on multiple prototypes.Aren't Team Asobi working on an Astro platformer? They probably started it sometime in 2020.
True, they don't expect all games to be massive hits and many games are there to cover certain niches in their portfolio adding variety, prestige etc. If they would only look for massive hits then Team Asobi and their Japanese XDEV team wouldn't exist because they would have shut down Japan Studio in the PS1 days.Money isn't the only reason publishes, especially platform holders, should (or even historically, have) used to develop and publish games. Besides not all games are expected to be massive hits, but the few which are tend to make more than enough profit to cover the costs of the less successful games. Isn't that exactly the mentality Sony have stated behind the (at the time) GaaS/live-service plans? They just need 2-3 big winners to cover the costs of the rest; why wouldn't that apply to traditional games and platformers specifically?
Plus, it helps with adding genre and game type variety to the portfolio of software offerings specific to the platform, which will entice additional sales of hardware and software over time. And, given this is a creative-driven industry, that type of variety gives more chances for artistic expression which a lot of creators in the industry want to do (in addition to making financially successful games of course).
And yes, with the profits of the most successful games they compensate the other ones that failed, it isn't only applied to GaaS. Same goes with their business segments or divisions.
But aside from having a good catalog and variety since they are a business they focus on what they think can give them more money because it's a business, which in the case of 1st party is narrative action adventures and GaaS. Games like Ratchet, Sackboy or Astro are very secondary for them.