I dont think there is enough data either way to support either side. I mean if there was no 3ds would Wii U be doing that much better? If there was no Wii U vice versa? cause if i recall 3ds was out on its own and it wasnt exactly doing gangbusters. and IMHO it still will end up with a massive drop from 3ds numbers. I think this whole Ninty fix thing is a bit exaggerated. Yes they have a large fanbase but it isnt that big.
On a side note anyone who doesnt think 3ds version of Smash will effect Wii U one even a little bit is insane. Look at Sonic Lost World and Lego city numbers. Doing much better for versions that a much worse. Hell the latter game wasnt even advertised.