Discrete graphics with 6 hr battery life? 2020 maybe if battery tech goes up a few.
I dont think there will be discrete graphics outside of specialty applications in 2020. By then we will either use OnLive type setup for mobile gaming or APU's will be good enough, or both. We are getting close on both fronts right now. I just got HP dm1z and it will play Civ4, WoW, SC2 on low settings, for 4 hours on battery power. I think this is closest we got right now to what OP is asking for. Two more generations and we're there. So 4 years, maybe?