It doesn't look like there's going to be a need or opportunity for any long ranged sniping in Brink. An assault rifle with a scope is probably going to be the closest we'll get, and that should do just fine.
But you know there's gonna be players who will do everything they can to design a sniper rifle that behaves like a sniper rifle. They will experiment with weapon attachments and player abilities, and find the perfect mix, mainly just out of spite to the game - like a "ha ha, I made a sniper anyway."
I picture a lot of players choosing Engineer to snipe - for the damage boost. This could be bad, seeing as Engineers are a primary objective class, and seeing a that your team has a lot of Engineers, yet no one is completing objectives, could be frustrating. Players wouldn't know if the Engineer is actually an Engineer, or a wannabe sniper.