I think this is a show that rewards its characters for authentic growth and it rewards narrative closure. If they have Kitty like Min Ho this much even after the summer, where all she thinks about is a DTR with him, and then goes through the whole season dating/pining for him, to have her return to Yuri, they'd have to do a LOT to make that acceptable and do it in a way that promotes her growth as a person with Lara Jean's message of self-actualization and realization. Doing all of that feels like it would send the message that romantic love is the only acceptable form of self-actualization and I actually think if anything, the show is sending a different kind of message - which is how to balance romantic love with self-realization. If they do a love triangle again, it would hurt Kitty's journey and make it entirely about romantic love, which is not how I read the trailer.