For people who aren't and won't watch the Q&A, Fishman did answer a question regarding watchalongs. He said that he's suprised of the amount of people mentioning it, how its a form of marketing and a matter of budgeting. Even though he didn't confirm or deny watchalongs for gen 3, he definitely didn't sound entirely against it. I guess we will learn in a few days anyway but here you go.
Speaking of marketing, it seems that gen 3 videos are being used as ads and they are relatively successful, especially the covers. I didn't encounter any ads myself, but there are people who comment they got them and liked em. Marketing gen 3 and their debuts in general seems to work really well so far.