If the price doesnt rise then the miners stop mining because of lack of profit, Once this happens the network becomes less secure and bitcoin starts dying off. Whats to stop this from happening? Maybe we are getting to prices that cant be maintained with the current user base. I wasnt here at the last halfing and the price will need to be much higher so im not too sure what will happen.
Miners have more coins then everyone else so they are the one who define the price (they won't sell if it's not profitable for them) , beside ... logically Bitcoin price is based on Supply and demand , so It's impossible for the supply to get halved and the demand stays the same or rise and nothing at all happens to the price ...