I doubt that subsidies really hurt the carries bottom line. About 3 years ago when I was last switching carriers, T-Mobile used to have two plans that provided the same minutes/text/data; one plan provided a discount on the phone but were required a two year contract while the other had no subsidy and no contract. In addition the plan with the subsidy cost $20 more a month for smartphones with dataplans. The typical discount on the smart phone was $250-$350. But the extra fees you paid over the life of the contract was $480. So over the life of the contract, you paid an extra $130-$230 to the carrier in exchange for a low start up cost.
(And T-Mobile had a similar thing with regular phones; charged an extra $10 a month / $240 over the life of the contract for a discount of $100-$150).
I highly doubt that any of the other carriers don't also make back the subsidy by higher per-month fees. Of course, I also wonder now that those carriers have gotten people used to a certain monthly fee, will they really lower them after taking away the subsidy.
One of the reasons I liked T-Mobile was that they gave me the option.