Er, I doubt that's the case. She has already been recast once, from Howie Mendel to Frank Welker. Both voice actors are still alive. And I'm certain that if they aged her they'd recast her voice. Welker is amazing, but somehow I don't see him voicing a peppery young woman.
Probably The Powers That Be just see Skeeter as non-canon. She was created to be another female in the nursery, and when that need was gone, so was Skeeter.
Last I heard Nanny threw her out in the trash, and she's now living in the dump with friends made of garbage.