For years, T-Mobile had great success with the Sidekick line of devices. That is before the smartphone market really blew up. Their most recent effort with the line can't be called a success, despite the fact they teamed up with Samsung to create the Android 2.2 powered Sidekick 4G with all sorts of (at the time) updated customizations.
Perhaps that's the reason T-Mobile is sending the brand into retirement as confirmed to Phonescoop. Yep, it'll be a while before we see another Sidekick branded device come onto the market. However; T-Mobile was quick to point out they're not discontinuing the line. Instead, just giving it a little rest and relaxation. Go on; pretend to be surprised in the comments.