I think the poll is closed now. I believe it will always be a niche, but don't expect to make a great deal of money on this particular niche. It's an interesting angle and can be profitable, but if you get into it, treat it like a part time job.
It seems hard to take numeric domains seriously because they are usually associated with spam or fishy websites. As far as I know, only Asians are so attached to lucky-or-unlucky numbers, unlike Westerns. Perhaps that's why the appeal is very low to regions outside Asia. I don't think I've ever seen websites with numeric domains.