There will be one more season. This is split up into two 8 episode seasons. The first 8 are airing now and the next 8 start shooting in November and air next Summer.
Walt's been pretty interested in getting rid of mike. Maybe he'll try and hire the kid killer to take him out? 3 more episodes and then we have to wait til next summer for it to wrap up. :(. Show is still great and I love how the intensity is ramping to match walt's spiral into shitheadedness.