I agree that from where we stand now, it doesn't look like The Shield will go much further than 2 more seasons. On the other hand it's hard for me to believe that the money train actually happened two seasons ago. When Lem burned the money and Shane and Vic had their big fight, I didn't know what kind of show I would be in for if any.
I can't stand Shane either, but without him The Shield wouldn't be what it is. A lot of the edginess rides on the question of whether he's fiercely loyal or just out for himself. This is what made the season with Antwon Mitchell so exciting.
What Lem dying really does is unveil the Strike Team for what they really were. Up until this point I was always rooting for them and found them all appealing in their own way and I know pretty much everyone feels the same. Now I just feel like I'm waiting for Vic to kill Shane. And while Lem really was the good one, when he tells Becca she should "open her goddamn eyes to who we really are" he's holding himself up with all of them and saying he shouldn't be excused from it.