If they make the sensor/countersensor tech more important (which the video they've released suggests they will) then light mechs will become an important part. In MW4 it didn't really matter, other than to let you know a little earlier what was coming your way. You couldn't really use it to evade the enemy.
Of course, getting the AI to not know where you are is always tricky, since the computer knows where you are by default and only has to ask itself where to find you like the cheating bastard that it is.