User blog comment:JakePT/Mass Effect 3 to be Revealed at VGA Awards?/@comment-216.40.154.60-20101122062021/@comment-1221773-20101122065451

Compared to the ME galaxy, Earth's history between now and then would be relatively boring and un-ME-like. You go back before 2148, and humanity isn't even aware of mass effect physics and is nine years away from encountering extraterrestrial intelligent life. Guns probably still used bullets. If BioWare is setting this so far back in time, they might as well be making an entirely different game regardless of any "Mass Effect" in the title. It's the sci-fi that makes ME what it is.

As for the Incisor's age, It would appear that it's a recently (relative to 2185) developed weapon, part of a "new wave" of police weapons. Given the differences between the Incisor seen in ME2 and the alleged one in the teaser screenshot above, it's possible the screenshot one is a prototype, or even a more advanced version. But in either case, I wouldn't put it too far from 2185.