That said, here're my thoughts on it:
- Goblins are notorious for their love of money and economic-manipulation. Aligning themselves with only one faction would not only go against goblinish ways (in fact, aligning with Horde is cutting out the significant client base that is the Alliance), but also really throw the cross-faction AHs in the air. Language barriers would truly come into question, as well.
- Worgen are, lore-wise, akin to the undead: abominations/twisted versions of humans, in many cases, due to Arugal's curse, though the original Worgen are from another dimension. How many of those once-human worgen were willing to undergo that curse? How open would the family be to discover their child, their mother, their father, their neighbor was turned into a Worgen? How accepting would they be? Would it be a "Aww my son turns into a big fluffy puppy now! Hey, you'll now be an even better shepherd, and can sleep on the hearth rug. Here's a bone, Spot!" ...or would it be a "Oh, lord, why has such black magic has fallen upon our family?! Out with the beast, before it eats us all! Let us mourn the loss of our son, and destroy the beast that has taken over his body!" Yes, the Worgen were originally summoned by a human and a night elf, but they also just as quickly turned upon their summoners. I can't see them seriously aligning voluntarily with the Alliance en masse. It would also require a reworking of Silverpine as it is a "no PvP, Horde-baby-leveling" zone, akin to the Barrens and Darkshore; allowing alliance to have a shared 10-20 zone with the horde is unheard of thus far in the game. If Worgen do become an alliance-only race, I would see them more likely starting down in the Duskwood/Redridge area.
We'll see what happens. I'm eyeing the whole thing guardedly. I'd LOVE to level a worgen druid, though... if I can roll one as horde, I'd gladly play a worgen druid over moocow! ;)