Is where I think he will finish his career. It's the only smart thing for him at this time. The middleweight division is currently at a stand still. Only 3 guys currently posse good records to bid for title shots. Weidman(5), Belcher(4), and Boestch(3). Each guy lacks one thing.. Star power. Weidman and Boestch are currently booked, but a win over one another wouldn't necessarily jolt them into stardom. Belcher is mending an injury and with Vitor jumping up in weight, Stann and Bisping set to battle, Lombard and Palahares squaring off and Munoz working on his diet and a foot injury, he's currently left without a top contender to build his resume on.
Silva, currently riding high on a 13 fight win streak in the middleweight division is left scratching his head. He's defeated the top of the heap, Chael(2), Marquardt, Henderson, Belfort, Franklin(2), Maia, Okami etc to name of few of the top guys who made it to the belt, but jus coildnt take it. Silva is in need of a legit name, a serious threat(not saying Belcher or Weidman ain't, but a threat Silva feels is a threat) and that star factor.
Insert him into the mix at 170 and he has all those crammed into one stacked division. He's been begging for a superfight with GSP. But with GSP coming back from injury, a title unification bout on the horizon, and plenty of hungry challengers in the wing, that superfight may not come to, or at least not soon.
Silva says he has roughly 6 years, which is 4 less then the last time he stated how long he would continue to fight. I see a permanent drop to 170 as his window to make sure, there will never be another if and or but about him being GOAT. He has the frame to make the cut. Guys like Diaz, Condit, Kampmann and Marquardt are all big tall or lanky guys of the division. Diaz, Condit and Kampmann all exceed the 6'0" mark and Kampmann and Marquardt are both former 185 lbers. Silva being a lil flabby and standing around 6'2"(same as Condit) I believe could make the drop with ease.
Throw him into a title bout with either Condit or GSP, whichever wins, and get his legacy on the way to an end. With a title win at 170 an at least 4 solid defenses, we could see the end of by far the most impressive, flashyest and dominat fighters the MMA world has seen... Ever.
P.S. Vote me up please. 
percycanfight - P.S. Vote me up please.
Didn't read because it's way too long for a purely speculative post but I had to comment on this:
Are you seriously begging for up votes? Wow.
I have still have to wait until my 24 hours expires.
But when it does...VTFU
I agree with weight cutting the way it is nowadays he's a natural ww, I don't agree however that it would somehow be a bigger challenge. After he fought gsp then Diaz there aren't anymore fights that are all that interesting. 
I don't think he is interested in training and watching his diet between fights to the degree that fighting permanently at 170 would require.
orcus - I don't think he is interested in training and watching his diet between fights to the degree that fighting permanently at 170 would require.
Probably true
And OP, Bisping is probably the most likely guy at 185 to get the title shot. Its the best money fight they can make at 185
bornop - Condit vs Silva would be excellent. There are a lot of interesting fights at 170 for Anderson, and GSP would not have any excuses about weight
Condit vs silva? Really? Be honest with yourselves does anyone here give Carlos condit any chance in that fight?
While he would probably do ok at 170, (smashing gsp, surviving diaz)he would probably lose to marquart if they met at marquarts de-roided size.
Lol. Wasn't begging..
Jus don't know why I'm at -10
I think people abuse the vote downs.
And Silva is more interesting at 170 cause the guys there would scrap. At 205, I'd predict a lot of the guys tryn to wrestle. Evans, Jones, Sonnen, Davis, Bader.. they'd all take the fight down. Shogun would scrap. Machida wouldnt take the fight. Glover probably not either. Gus, not sure how'd he fight that fight. And Hendo.. probably takedowns since that's what he did at they're 185 fight.
I think theres a lot more strikers at 170. I'd rather see scraps then dry humps.
Voted up, as promised.