The Army is working on upgrades to the Abrams tank to keep it operating through the 2020s. With no new tank in the design pipelines, this is good.
The new M-1A2 SEPv4 will have a number of improvements, including what I think is most important--an active protection system to push the line of defense out from the bulk of the armor's passive protection.
Outside of the frontal arc--and even in the frontal arc if we face top-attack missiles--our tanks can be killed. Active protection is the only reasonable answer to this problem.
The evolution of the Abrams fits with my critiques of the Army's past effort (see "Equipping the Objective Force" in this issue of Military Review) to leap beyond the Abrams to get a wonder tank (the FCS) that combines lethality, survivability, and strategic mobility.