It may be worth remembering there was seven years between the original Hills and the follow-up to it. Which may or may not mean anything, but it's an interesting comparative statistic.

There's no inherent reason why a fast turnaround shouldn't work, as I don't think a film like this really requires large resources of time to be spent on it. Obviously you don't want it to be pushed out too quickly, but at the same time labouring too long over it could also be counterproductive. I'm more concerned (like you) about the absence of Aja. I saw the remake just the other day and, apart from a few considerations generally enjoyed it, although I don't think Aja did much with the scenario until the last act and the whole business with the ghost town. That was when it suddenly became immensely good. He'll be a director well worth watching in future, I think.

Hard to tell about Bassett. I've seen neither of his films, though at least Deathwatch sounds interesting (Wilderness sounds a bit more of a yawner, though). It could work out. That said, it's impossible not to sense a certain whiff of desperation on Fox Searchlight's part (I'm presuming they're doing this sequel too), trying to exploit something as ruthlessly as possible... cos Aja's remake appears to have been successful enough to actually almost turn a profit just in the US (if you take the usual wisdom that you need to make back three times your budget to actually go into profit; it returned its budget and then some just on the opening weekend), no doubt at least in part cos it was relatively cheap ($11m, according to IMDb). The question will be, if this sequel is a cynical cash-in (and on the surface I don't know what else it is), will the end result look like one to the point where it'll piss people off or not.