Someone has scheduled a bunch of last minute late night appearances scheduled for this Thursday. ATRL, the pop KTT, suggests that this could only be a major artist and many think it's Adele. Rihanna could also be a possibility.
I'm personally going with Post Malone... he's already announced that his album is complete, his tour is already scheduled, he has an event tomorrow where he may formally announce the album and there is a counter on his official merch site which ends tomorrow:
What do yall think?