They'll probably film one All Star season and Season 16 back-to-back while AS8 is airing and then maybe film another AS variation while UK5 is airing.
Even this is unlikely. World of Wonder is notoriously cheap and they purposefully film seasons that share studios back-to-back to save production costs and staffing logistics. It's why each All Star season films directly after the regular season, why they filmed UK vs the World directly after UK3, and even Canada vs the World immediately after Canada 3. They send one cast home and the next season begins filming the following week with no breaking period for the staff or judges because it's easier and cheaper that way. If they are planning an additional US season to be filmed next year, they wouldn't be filming it as UK5 airs in the fall, months after they've closed down the sets and sent production home from AS9 filming, it'd be back-to-back-to-back with S16, and AS9. Based on Dragcon LA being in mid-May 2023, UK filming will need to be done by then and S16 will likely film soon after with whatever All Stars immediately after that.
Paramount Plus, which would be the likely home of the alleged All Winners 2 and US vs the World seasons, wouldn't even be able to air anything in the first half of the year due to exclusivity deals with VH1 and the regular season so 2 All Stars seasons would both have to air between June-December of 2024.