Good question! It's possible that this will eventually happen, but I think it's unlikely for 2 reasons:
Lots of stuff goes through a small area in the carpal tunnel so it's easy for it to all rub too much and get irritated. My understanding is that the extensors don't all go through a similar narrow area so are less likely to have this problem.
The flexors are used a lot for typing. By moving some of the wear from mousing to the extensors, the idea is to better spread out the wear and tear.
One note of caution. Until you have a lot more data from a lot more users, this is not an ergonomic mouse, but is more of a test platform to test the idea of whether this is an ergonomic mouse.
Lots of stuff goes through a small area in the carpal tunnel so it's easy for it to all rub too much and get irritated. My understanding is that the extensors don't all go through a similar narrow area so are less likely to have this problem.
The flexors are used a lot for typing. By moving some of the wear from mousing to the extensors, the idea is to better spread out the wear and tear.