IMO, the only thing that is really holding back Blu_Ray at this point is the price tag. $300 for a player, and movies running around $30-40 each, its still VERY expensive for most home users to be able to get into.
The people who could afford the players now already have them, and also, more companies are starting to manufactor the players as well. Its only a matter of time until we see the no-name companies making their own, as they did with DVD, VHS, etc..
The only other thing that really hindered the growth at its time was HD-DVD, but since that is also now defunct, Blu_ray just needs a lower price point, and I think it will start to boom again.