Thanks, I agree with you. As it exists today, Magic Your Way (MYW) tickets have nothing to do with onsite vs. offsite guests. In my head (which I didn't explain in my post), I think of my "Key to the World" card as a different physical "ticket", which it is not. Instead, today's "Key to the World" card can be considered as containing my MYW ticket on it. I am speculating (just speculating) that there will be "bonus" FP+ for onsite guests, which currently are people who have a "Key to the World" card. However, by itself, a "Key to the World" card is not a ticket.
I suspect TDO has plans to recoup its $1.5B investment in NextGen. Since it's been posted several times that guests won't explicitly be charged for FP+, the only way I see NextGen not being a financial sinkhole is if FP+ is used to somehow increase onsite hotel occupancy or as a replacement for Extra Magic Hours (EMH) & "Free Dining".
All this is just speculation but I hope it makes sense.