If Disney World reads MiceAge, they give no official indication. Every so often, though, there are hints of it.
After months of watching the paint on TTC crack, peel, and look ugly, I spoke up about it online and had pictures. A few weeks later, it was repainted.
After months of watching bird poop accumulate on benches in Frontierland, at the waterfront walkway, I said nothing, and watched as the benches were sometimes cleaned nightly, sometimes not. Finally I commented online about the wax and wane of the problem. That was done twice, six weeks and four weeks ago, without seeing the benches much in person in between. Recently I made my way back to this part of the park, and saw that the walkway now sports no benches at all.
Perhaps they were simply missing that day and will be back. Or, perhaps someone with the power to decide came to the same conclusion I did, that the benches were problematic, and simply needed to go. In either of the above, MiceAge was not a factor. But I do wonder.