Too expensive is the big problem but it's not the only one. Android has seen many attempts to sell devices with physical keyboard's, outside the ultra low end, where a keyboard can improve on a poor and small touchscreen, the market rejected them all.
For all we claim to want them, on modern devices we don't need them and once that sinks in we choose the smaller, lighter version. I even carry a keyboard case with my tablet yet never bother using it as anything but a case and kickstand.
Blackberry fulfilled a need that no longer exists. It probably would have sank even on their own OS with today's hardware.