No single aspect is enough to make a decision

The value of a service is determined by how much you get for how much you give.

If I give up a two-year commitment, I might gain in terms of special rates over that time ... or not. For me to compare a month-to-month with a two-year plan, I would need a projection of overall value. Perhaps the two-year plan offers cheaper unlimited texting, or a better international plan, or a better rate for families. If the competitor's rates are higher, but not much higher, the two-year company might contract to always match the rates of certain competing companies.

My guess is that company's like Verizon will start offering something like an "Easy Out", where you can drop out after a certain point without incurring a penalty, and offer persistence incentives for those who don't drop out, perhaps in the form of free apps (especially games) or other special services. It is also likely that will offer company-linked options that create dependence on the company (like Comcast's seven free e-mail addresses which would be a real pain to give up).