The price would be an increase for some people.
Take my plan for instance. Right now I buy my iPhone from AT&T on a subsidy for $200. The normal full price is $650, so the subsidy is $450 less.
Now my monthly cost of the contract is $50/mo. It's a 5-line FamilyTalk plan which costs $60 + 10 per additional line ($100 for 5 lines so $20 per user) and then plus whatever your data plan is. My data plan is $30/mo for unlimited data. Adding both together makes my monthly share of the bill $50.
If we take the $450 subsidy amount and divide it out into 24 months, which is how often I get another subsidy upgrade, that's $18.75/mo. There is no plan to get equivalent service to what I have now for 50 - 18.75 = 31.25/mo.