I'm going to go against the general opinion and point out a few things. Those saying that it's impossible are wrong...
First of all, the Uzumaki are a CLAN, not a village, and they are mostly extinct so don't really have a place they're meant to stay at anymore. Their members do not need to be from Konoha. Karin, for example, is not from Konoha, but is an Uzumaki.
Secondly, where do people pull up this "fact" that all Uzumakis can survive Bijuu extraction. 1 Uzumaki survived an extraction through her will-power. Nowhere did it say that "Uzumakis can survive extractions." If it did say something like that in the manga, please pull up a scan of that part of the manga to shut me up. SO, Gaara not surviving the extraction doesn't mean shit.
Thirdly, the fact that Gaara's family has no surname also leaves it possible, and the fact that Uzumakis can have children with all sorts of hair (i.e. Naruto) means that although Gaara's siblings have completely different hair colours, it's perfectly plausible that they're Uzumakis; and they don't seem to have any chakra issues/problems.
Following from this, it's actually still plausible Gaara is an Uzumaki, but I doubt Kishi will do any sort of reveal like that at this stage, and if he doesn't do a reveal, then it's simply not true cos Kishi saying so is what will make it true.