Between this, the fact that both bikes have been modeled for in game, and the advertisement keeps emphasizing the winning side gets a "Free" bike, this is likely to be the case. However, they're likely to not say anything till closer to 6.0, to lessen it undermining the entire competition.
There's actually no evidence that the bikes are already done; if they were they'd have shown us already.
Sure, the first chopper could use some Alliance signifiers, but then it isn't really an Alliance bike. Alliance-themed, perhaps, going by the colour scheme and the lion (then again, that's not rare at all), but if they added some Alliancey stuff to that first REAL chopper, that one would be a thousand times better than what we got.
In comparison, the Azeroth Chopper just looks.. horrible, tacky, and .. overall -- just blugh.
You know, I have to pick the one from Paul Jr. designs/Blizzard more than the first one. The first one doesn't feel right or fitting for a WoW universe. If I had to pick of those, the Alliance one more. First one looking too fragile for our world.. "Shit.. Dragon swiped me... Better get aw-.. crap.. it broke my chopper"