Almost nobody is saying "I want 4G and I am willing to pay more than I am paying now for it". Almost everybody is using steadily increasing amounts of data, applications that work better with higher speed connections, and therefore gradually need speed improvements. With that comes an expectation that data will work everywhere, so better coverage of data services is needed to.
LTE is vital to deliver these things in medium term. (LTE on 800MHz is vitally important for the better coverage issue). Networks who try to sell LTE as a product in itself at much higher prices than 3G (I am looking at you, EE) are not going to succeed. Networks who try to sell it at a premium to corporate customers and provide a high quality network (Vodafone) are likely to find slightly less resistance, but still need to answer the question "What is it for"? Networks that just advertise their "fast network", state that LTE is included on the tariff, and provide this every increasing speed of service to their customers (Three) may do well of it. (I will not even try to figure out what O2's strategy is. I am not sure even they know).
My phone is presently a SIM only deal on Three. I am perfectly happy with the HTC One S I have at the moment, but for my next phone, I will probably stick with that contract and buy an LTE capable phone up front, if it doesn't cost too much and I hear the battery life is not too dismal. There is a fair chance that I might need to upgrade from my present 1Gb a month data allowance to a deal with an unlimited allowance, so they might get a few quid out of me that way. Or perhaps I will get a contract with fewer talk minutes, and the cost will stay about the same. I don't ever seem to go near my current allowance.