The solution to this is simple: Don't plan around EMH and do assume the park will close at 10.
If you end up with bonus hours, awesome. But don't count on them, don't plan on them, don't work under the assumption they are coming. And if you don't see value in 9-10, then don't go. But WDW is going to shuffle EMHs around, and they're going to be quiet about extended hours, too, until they make a real call on DAH, and I don't think they've made that yet, no matter how unsuccessful it's seemed so far.
Crowd calendars have been wrong, park hours are subject to change and a whole lot of Disney scheduling is in flux these days. You've got EMMs and DAHs to consider, too. So plan around what you know, not what you expect.
As far as I can tell, nobody's ADRs are affected, just their presumptive plans. And there's one thing that's become apparent to me this year is that presumptive planning doesn't work at WDW nearly as well as it used to, so it might be best to plan around what you KNOW will happen -- plan for 9-10, and adjust from that on the fly. I think anything else is a recipe for going crazy.