I think it will depend on the time of year.This is why I think 7 am switch scramble may be moot, and it’s the refreshing and drop times after the parks open that may be the best bet. You’re right, availability was generally crap when you got close enough to the day but was workable if you knew how to mess with it during the day.
On the average day how full would the Disney resorts be? Say it's 50%.
What portion of those people are willing to pay for the Multi pass? 1/2?
Using those numbers there should be lots of inventory for the power users.
If the resorts are full....which seems like a stretch for the next few years....then it's a different story.