The two leading wireless carriers in the United States built up huge smartphone user bases while luring customers in with unlimited data plans. The writing was on the wall years ago, however, and as mobile data usage exploded, Verizon Wireless and AT&T both dumped their unlimited plans in favor of tiered data offerings that slam users with overage charges if they use too much data in a billing period. Sprint and T-Mobile continue to use unlimited data plans as a point of differentiation with their larger rivals but as one analysis pointed out this week, the days of unlimited data at Sprint and T-Mobile are numbered.

Writing at PCMag, longtime wireless industry reporter Sascha Segan has penned a piece that sheds light on a simple truth U.S. wireless subscribers will all soon have to face: Unlimited mobile data plans are dying and there is nothing we can do to stop it.

AT&T and Verizon bailed on their unlimited plans years ago, as data-hungry apps and streaming video and music services began to hammer their networks. As more data-gulping mobile services roll out, no network will be able to withstand their insatiable need for data.

Also of note, maintaining unlimited data plans hasn’t really seemed to do much in the way of helping T-Mobile and Sprint add subscribers.

Sprint continues to struggle against rivals despite marketing its unlimited data plans very aggressively. Meanwhile T-Mobile is adding new subscribers at a shocking rate but its success is the direct result of CEO John Legere and company’s recent “Uncarrier” initiatives, which focus on various subscriber pain points while pushing unlimited data offerings into the background.

In other words, the remaining nationwide carriers that do still offer unlimited data don’t have much of an incentive to keep their unlimited data plans around.

As Segan noted in his analysis, T-Mobile is now shifting its focus away from unlimited data plans. In fact, the carrier just made its all-inclusive unlimited plan more expensive while slashing prices on tiered data plans. Sprint has more room for unlimited data plans thanks to its much larger spectrum stash, but it looks like trouble is brewing there as well.

“I’ve been hearing murmurs from Sprint insiders that the unlimited data gravy train may eventually have to end, though, if usage trends continue to arc upwards and if Sprint is at all successful in gaining customers,” Segan wrote. “Like with AT&T and Verizon, this will probably mean that existing unlimited users will get to keep their plans but new users will be forced onto the same metered concept that everyone else is seeing. (In other words, if you want Sprint unlimited data, go get it in the next year or so.)”

To this point, users with old unlimited plans have been able to retain them if they’re willing to forgo certain features and pass on newer, cheaper service plans. That capability will likely remain, but carriers like AT&T and Verizon already throttle unlimited data plan holders once a certain threshold is reached, so these plans are basically now “unlimited” in name only.