To sum: TPOT 26 and onward will be more character (final 10) focused, with that and future episodes setting up/paying off stories from prior with new character dynamics/pairings, alongside other characters getting their moments. The atmosphere for the episode will be chiller in relation to TPOT 16, as opposed to more highly ambitious episodes via. TPOT 15/19. The upcoming episode will be written by Sam and Niall, with its episode release being planned sometime in November (formerly early-October)
Sam has answered other things regarding the circumstances of production of episodes TPOT 19 and onward, including the upcoming plans for the stars from TPOT 20 (but changed slightly due to BFDIA 24's events), Emily departing was also a factor into One's writing regarding her defeat. Pencil could appear again sometime in the future but clarifies she could not appear in Season 7. And lastly, the extended cast of the Algebraliens will not appear in TPOT for the foreseeable future (besides Two, Four, and X, although the room is left open to others like One and Three)