You might want to keep an eye on the Orlando Hotels board and reports from those who have stayed recently (or as it gets closer to your trip). I believe at least some of the off-site resorts had suspended shuttles to the parks this summer/fall. I don't know if they have resume yet.
In the past, some of the shuttle services may have used accessible buses. You'd want to check with the specific resort to ask what is the process for making sure you have accessible transportation. I believe some will call a cab is the bus doesn't have a lift.