The market for HT is always there, but depending on where you live, cracking it isn't so easy. Where I live up in Northern California, there are only two places to get audio gear within (literally) a hundred miles, and one of them is Best Buy. Since that is what people in the area generally know about audio, it is practically an impossible market to crack. I have and still am considering opening an audio shop up there, so I applied to the one independent place up there and he said there wasn't enough work to justify bringing me on. If and when Best Buy goes under, that may change quickly though. I intended to do custom installation and calibration and that's a difficult one for people to spend money on because everyone thinks they can do it right themselves.
In the Bay Area, where I spend most of my time because I work here, the market is considerably different because there are a few high end shops and plenty of customers.