no it won't don't be a ignorant fool not with all the gen 5 mechanic changes team preview and the new pokemon.
What gen V game mechanic changes?
EDIT: uh uh i'm gonna make a list
Sleep Counter resetting on switch
New moves like Shell Smash, Icicle Crash, Wild Crash, Dragon Tail, Circle Throw, Scald, Clear Smog, and I can't really think of many others
Tail Glow being +3
Some random abilities that did things nothing did in gen v (Prankster, Magic Bounce, Sand Rush/Sand Force, Sheer Force, Regenerator and Imposter being some of the big targets that oh yeah this metagame would barely have because of DW restrictions :/)
Multi hit moves getting boosted in power and even awesomer with technician
High Jump Kick getting boosted too
Rotom-Forme type change (snooooooooooooooooooooooooooze)
but seriously Gen IV to Gen V is pretty much the same game entirely, it's the least drastic game mechanic shift generation to generation so far, and IV was closer to III, than III was to II or II was to I. No physical special split, no total rehauling of stat allocation, no addition of two entirely new types and an actually entirely new mechanic (held items). On the other hand, obviously Gen V had the most new pokemon added to the metagame and they'd be least affected by the new dream world thing. So I can kinda see where you're coming from, but I think it would just make a lot of the older pokemon a lot less powerful. Espeon wouldn't be touching OU with a ten foot pole without magic bounce, and so would basically I guess all the old pokemon except stuff like Tyranitar and Scizor, that were already pretty threatening no matter what in Gen V. But yeah, without DW there are for a lot of older pokemon no gen V game mechanic changes at all.
Still I vote a better name for this tier is release date, in that it has all the pokemon accessible as of the japanese release before dw first got set up. It's basically the OU metagame frozen in that moment in time like a piece of amber. But yeah, probably one of the coolest things about gen V compared to gen IV is how dw releases keep the metagame shifting around over time, though i was kinda hoping they'd save something other than shadow tag chandelure for after bw2 comes out :?