While we're still receiving patch 10.2.5 PTR updates, Blizzard seems to be spinning up a new PTR branch in parallel, showing a signature for Patch 10.2.6.
While we can see that build number, this branch is completely encrypted so we can't datamine it at the moment.
While Blizzard hasn't published a roadmap for 2024, it seems that their patch cadence will stay similar to 2023's, with different PTR patches being worked on in parallel.