I actually expect the price of plaintext HTTP hosting to go up a bit; partly due to reduced demand, but also due to increased risk/liability. With SSL being the "industry best practice", I expect at least a few bean counters will view the risk of private information leaks or hypothetical legal liability for enabling DDOS (similar to the "attractive nuisance" doctrine).
There will be a turbulent transition period, of course. As someone currently living at the poverty line, I have argued against the CA system many times. A SSL cert (and anual renewal) may be an insignificant cost to some people, but it is a real barrier when tha cost represents days/weeks of food. Unfortunately, none of this removes the need for encryption or the risks of plaintext. This is why I'm very excited about Let’s Encrypt; It might solve the cost problem, and it might avoid the StartSSL "no second-source" problem because it is a protocol first.
Internet use is only going up, so these transition costs are only going to go up. We can pay it now, or pay even more in the future.