Barring the announcement of a new device, it looks like T-Mobile’s Sidekick brand will again be going on hiatus. As of last week, the T-Mobile Sidekick 4G has been discontinued. The phone, which was released last year, revived the line of proto-smartphones with a fresh Android operating system and increased functionality. Still intact was the slide-out QWERTY keyboard that put Sidekick hardware on the map. The result was a surprisingly nice mid-range handset that lived up to its pedigree. We haven’t heard much to suggest an updated Sidekick is headed our way in 2012, but given the line’s history we wouldn’t rule it out.