Is everyone going to fall asleep after Zapados?
I will give this to Niantic they are doing a great job keeping everyone active by introducing the Legendary Birds one week at a time. But what happens after Zapados? I foresee a lot of inactivity. Main reason is the extreme difficulty of collecting Stardust. After two hours of grinding Pokemon and only being able to power your mon up once is going to become very very very dull. Second reason the gym system is also not competitive and the rewards aren't worth the potions. Raids are going to die out because everyone has spent their last dollar on Raid Passes for the Legendary Birds. If Niantic doesn't think of something fast there will be a dreadful drought in Pokemon go.
Answers
I'm going to be so active during the Zapdos raids. Anyways, I definitely think there SHOULD BE a nice big break until the next set of legendaries appears. Like you said, people have been active, they have spent they're money. It would be nice to take a break from all the legendaries. They could mix things up with the gyms. Maybe release Generation 3? I definitely don't want to see any more legendaries any time soon after Zapdos. You've been given more than enough legendaries for now.
Oh, and a part of me hopes they hold of Mewto until some time next year. Because the moment I get him, if I get him, there won't be anything for me to go after really...
I just hope for a break. It´s quite tiresome to have these time limits to catch the most-wanted pokemons. If they continue right now a lot of people will get fed up, and when it´s back to normal a lot will fall asleep for a shorter or longer period.
Let's just get back to normal business with grinding and planning for the next release. Maybe someone will show up to Ttar raids again, since it´s really more valuable than these birds.
While the group raiders take a break, maybe they'll do something to bring back people who haven't had sufficiently large raid groups in the first place - so that those people have a shot at the new game content too.
Stardust and coins aren't a problem for players like me. I haven't found a good use for either in quite a while. They have to think of a better kind of activity to incentivize than driving (and/or sitting around) for hours, just to sit or stand by a gym for 10-30 minutes at a time.