The last information publically available (from several months ago) was that Disney would offer FP+ to all guests but that MagicBands would be an upsell to offsite guests.
Disney has stated that onsite guests would be able to reserve their FP+ experiences at 60 days plus 10 days from the start of the stay. Disney has never publically stated how far in advance offsite guests would be able to reserve their FP+ experiences.
Disney's original plans involved forcing guests to pick from groups, requiring those testing the system to select some lesser attractions. After overwhelmingly negative feedback, Disney opened FP+ selection to any 3 attractions within one park. Assuming this remains in place, anyone in a position to make their FP+ selections early will have a significant advantage.
WDW's problem at 3 of its 4 theme parks is ride capacity. It simply doesn't have enough high-capacity E ticket attractions at Epcot, DHS, and DAK. Allowing guests to pick any 3 attractions at those parks means that there will be many WDW (presumably offsite) guests who will be shut out of headliner attractions.
FP+ has the potential to drive onsite occupancy rates back up to historic levels while simultaneously driving away vacationers not staying at WDW resorts.
With Universal publically announcing plans to become "a family destination in and of itself, not an add-on attraction for somebody who’s spent three or four days someplace else", IMHO, corporate Disney is playing with fire.
The initial plans to force guests to pick from groups had the potential to more evenly distribute FP+ selections, somewhat placating offsite guests, even if onsite guests had a booking advantage. If offsite guests have no reasonable chance of obtaining FP+ selections for attractions such as TSM, EE, and Soarin', WDW could experience an appreciable decline in attendance at 3 of its 4 theme parks. Only the Magic Kingdom has a sufficient number of popular attractions to keep most guests happy.
Again, corporate Disney is playing with fire and might get burned.
Thanks for the thorough explanation. DW, DD and I go to Disney every year staying at an offsite timeshare. I look past most problems at WDW because as long as my daughter is happy so am I. That said, if we were unable to get FP+ to any of the E-tickets it would spell then end of our yearly trips to see the mouse. I would have to think others like me would either stop going or sharply reduce the time spent at WDW.