It's way too soon to be saying things like that--CC may have definitely made it BL in 4th Gen UU, but we know nothing of what 5th gen UU will be like. Even if Arcanine doesn't make it to OU and remains UU by usage, remember, these changes to Arcanine don't exist in isolation--there are 156 new Pokemon, new moves, Dream World abilities, other old moves being given more distribution. We don't know which of these new Pokemon will wind up settling down into UU, and how the other changes will affect the first 4 Gen's Pokemon's tiering. Depending on which Pokemon end up settling down in UU after all's said and done, even if Arcanine remains UU, it's definitely too soon to say it'll be a definite BL, because other Pokemon that can handle it fine could wind up UU alongside it.