In other we words "MHW will cost too much to optimise on the Switch so we wont waste our resources" expect MH5 on both Switch and 3DS.
Capcom had already confirmed that MHW is MH5.
Monster Hunter World is Monster Hunter 5 according to Capcom.
I wasn't entirely sure if they were serious when they said that, but if MHW is indeed MH5 then they could always resurrect the Freedom-series or something
Is was an official statement in response to fan questions, so I'm pretty sure it was serious.
I think it'd be better to call this the Generations series- Generations 2, Generations 3, etc.