I agree.I think if something were to cause it, it'll be Infinity War Pt. I & II and Justice League Pt. I & II. Those are gonna be four movies on a scale so unprecedented that whatever comes next might just fall completely flat.
With tv I don't watch any of them shyts but the netflix (Daredevil, Jessica Jones, etc)... b/c those are explicit R-rated type joints (a refreshing change) that follow that similar and proven path as the movies; i.e. Defenders will be their Avengers-equivalent end goal... and seeing Daredevil, Luke Cage, Iron Fist and Punisher all on the same show... with Electra, Jessica Jones, Misty Knight, Colleen, and even Hellcat involved?
sheeiiiiiiiiiit
But on network tv, i think the blatant cash grab ones that either seem purposeless or just feature D-list heroes will start to flop or plummet in ratings.. ala Agent Carter.
Regarding the movies: Infinity War 1 & 2 is to Avengers, what Avengers was to the first solo movies: the end goal of sorts. Once that is reached, that'll be one hell of a high to come down from.