This was a surprise! I have no idea why they decided to replace the cabs on these, but they're doing it. They probably had some money laying around they needed to spend. The only reason I can think of that warrants this is the fact that trim around the floors in some cars is destroyed (but that may have been done to get samples for the new cabs).
It appears that every elevator in each of the 4 towers is getting its cab replaced. Personally, I think the old cab looks a LOT nicer, but what can you do. The new cabs make the elevator appear very bright, and it's a little unsettling at times. The cars shown in this video are in the East Tower (aka the famous tower). I am not sure if the convention center and/or the parking cars are getting new cabs
0:00 Original Cab - Internal Car
0:55 Original Cab - Scenic Car
1:45 New Cab - Internal Car
None of the scenic cars had the new cab at the time this video was taken