Has this happened to you upon checking in?

[SueM in MN]

I believe the point is that HA accessible rooms are not "requests" and therefore it is highly unlikely the OP will arrive to find they have been bumped from the HA room type reserved. That would only occur in a relatively unusual situation such as the room had to be taken out of service due to a maintenance problem with plumbing or such. In that situation, as TheRustyScupper indicates, WDW will find a comparable room somewhere on property to meet the HA needs. This is a fairly rare occurrence considering how many guests reserve HA rooms each day. I'm sure to someone who works the front desk over several years would be aware of multiple incidents, but it is still not common.

OP, I wouldn't worry. If an unusual situation arises, WDW will do anything possible to meet your needs.

Enjoy your vacation!

I think lanejudy summed this up nicely and I am going to close the thread at this point.