If you look at any of the boxes with the little boost phones for sale, or actually go to their website, you'll see that Boost Mobile is not its own company, and neither is Virgin for that matter. They're both owned by Sprint.

Sprint's policy, ever since acquiring both carriers, has been to feed them the sloppy seconds from its table. What is Boost's best phone? Now, compare it to Sprint's lineup.

In short, when will Boost get 4g? As soon as 4g becomes so common for Sprint thast they feel they can afford to send a cheaper phone down the prepaid line. And even then, it'll go to Virgin Mobile first before Boost.