sprint storeSprint quietly confirmed yesterday that it would offer an unlimited data plan for its upcoming 4G LTE network, but if the market is any indication, those plans could change fast.

The company, which is the no. 3 wireless carrier in the U.S. after AT&T and Verizon, made the decision to switch from WiMAX to LTE as its primary 4G network, but it’s way behind compared to its leading competitors. Sprint will soon launch its LG Viper 4G LTE phone and it might debut a planned Samsung Galaxy Nexus LTE device soon too. As for the network, the company plans to have LTE in at least six U.S. cities by the middle of the year to cover 100 million Americans.

While Sprint is initially saying it will offer an unlimited data plan for its LTE devices, it might feel safe doing so just because there are so few markets where LTE will actually be available. As its LTE network grows and more consumers actually have LTE phones, it could easily change its policies to fall in line with AT&T and Verizon, both of which have caps on their 4G data plans.

One of the most important factors to Sprint’s potential LTE success will be an LTE-enabled iPhone that costs less per month than its competition. We expect the next iPhone to be LTE-enabled for AT&T, Verizon, and Sprint because the new iPad includes LTE functionality.

Sprint store photo: The Consumerist/Flickr