I really don't know if there's any use speculating whether we'll get an insane achievement in the line of Seriously... mind you, a lot of achievements in GOW3 fell under 'insane'... but is there any point denying or even questioning that they'll toss another Seriously achievement at us?
The only question is... exactly how mean could the next generation of Seriously be? Seriously was 10K kills, Seriously 2.0 was 100K, and 3.0 was 65 Insane Onyx Medals and Level 100. So 4.0... I think it'll be a button masher achievement, for sure.
My one worry is that the next game will incorporate re-ups into the achievements, and possibly 4.0, if that's the name they'll use for it. I'm not sure if re-ups for Judgement have been confirmed yet, but I'd be very surprised if there aren't any. I believe in GOW3 people got Level 100 within 2 weeks of release?
I guess we'll just have to wait and see if they both toss one at us and if they do, exactly how crazy it'll be. Any speculation?
Edit: I realized I didn't really say very well what I wanted Seriously '4.0' to be, so here's what I think it should be: Earning all achievements in Gears of War 1, 2, and 3; and then all the 'base' (non-DLC) achievements in Gears of War: Judgement. Sort of a "You've done it all!" kind of achievement.