I thought about this a little bit more. I don't think it is very likely.
TSMM's operational hourly capacity is something in the neighborhood of 1,000---some estimates are higher, some lower. An average operating day is about 12 hours, so 12,000 total rides. Word on the street is that the default FP ratio is 60%, so if that doesn't change, you've got 7,200 rides reservable in advance. An average attendance day in the Studios is something like 26,500. So, to book the ride full, more 1/4 of all the guests who end up attending on a given day would have to reserve this.
Doubtful, IMO.
"But what about the restaurants? Those book up right at 180 days!" Good question, but a completely different scale. BOG, for example, seats about 350 guests. Dinner service runs roughly 4:00 to 9:00, so figure they can turn each table 4 times each night. So, that's about 1,400 guests total. That's probably a high estimate; I'd be surprised if they can turn a table in 75 minutes---the "turn time" is the time from one guest sitting down, ordering, eating, paying, clearing, and resetting the table to the next set of guests sitting down. Plus, the tables aren't going to be full---odd-numbered parties will leave empty seats and so on. So, let's call it 1,200 diners per night. An average MK day is just shy of 47,000 guests. So, now we are talking about only one in 40 guests who have to book early to fill the restaurant.
There's also a question about whether TSMM is going to be every guest's first choice. During testing, you could not use all of your reservations on "headliner" experiences. For example, you could reserve two of TSMM, Tower, and Coaster, but not all three. And, once it's fully deployed, it won't be just the rides. Figure that Fantasmic will be in that first set too. Most families making early reservations might still choose TSMM and Fantasmic, but not all of them.
In fact, I'm thinking I might make liberal use of the "experience" reservations. Fantasmic is a pain to see---you either need to wait a good 45-60 minutes, or you need to commit to a meal at a really odd time. I often skip it because it's a hassle. However, the three rides are easy to see with no waiting: just show up at rope drop and ride them in this order: TSMM, Coaster, Tower. If I can reserve one of those in the evening too, it gets even easier.