Taylor, you make some great points!
Yes, of course what I said only makes any sense if the next game is a sequel to Yooka-Laylee. It might not be the best assumption, but I do think that's at least one of the games they're working on. (At least, I selfishly hope so!)
Regardless of the next games, DLC, etc., I think my overall point is that the Kickstarter goals can/should be a bit less rigid than some fans might like, provided the reason for not meeting them is good enough. In the case of Silksong, I don't think anyone minds that it's not the DLC they expected or that they don't have a release date, since the actual product appears good to enough to make those questions not matter that much. In this context, this could look like discounting the DLC-quel instead of giving it to Backers entirely for free. I for one would be happy with a small discount on a future game if it built on the foundation set by Y-L.
Theorizing about this would certainly be a bit easier if we had any idea how the team is currently delegating things. As far as I've read, we know the team has grown since Y-L, but also that there are separate teams working on different things at the moment. I think it would be weird to have a team potentially even smaller than the original Y-L team working on DLC while another team might be working on a proper Y-L sequel, and yet another may be working on Yooka-Laylee Kart Racing or something. If they split things up too much just to be working on more things I worry the quality of each one would suffer, as well as each one taking more time to complete. My point on this is that I hope that they are making the game they feel needs to be made, rather than half-heartedly fulfilling a Kickstarter promise from 4 years ago.
At this point, I'd personally rather them skip Y-L DLC and just incorporate any future ideas they have for the series in a sequel comparable to how Banjo-Tooie built on Banjo-Kazooie. It might be a bit narrow-minded, but I think the only DLC that really makes sense for Y-L is something like an extra world or purely cosmetic things like the 64-bit tonic, maybe some costumes like Mario Odyssey, cheat codes, etc. I think anything beyond that involving new moves or bigger design changes would look strange when tacked on to the original game, could even affect how the original game plays, and would be better suited for a sequel.
Beyond all of this, I am just excited to see what they reveal next!