It's different for Disney, because Disney has offered FastPasses for free and guests are used to having that as an option. Universal never had an offering like that. If FastPasses go away entirely and the paid upcharge is the only option, there are going to be a lot of guests who want it because they've become too used to having FastPasses. If you have to spend $250 a night to stay at a value with no express pass offering, or could stay elsewhere for $300 a night including both your accommodations and an express pass, I think a lot of people would go for #2.
However, and it's a big however, that will depend on how the system works. If you have two adults and two kids, and you have to pay for each individually, that's a gigantic expense increase and you can throw what I just said out of the window. At Universal everyone in the room gets one (I think -- I know we both received one without having to pay anything extra, but it could be limited to two per room or something like that), but I don't know how they price it out for families otherwise.