There are alot of rogues complaining about their dmg being worse than other classes, but tbh, you just have to work for it. Its perfectly normal that you don't top the meters if you just stand there auto-attacking, I done quite alot of instances now and I haven't been outdmg'd so far. Infact, last run I did 395,000 more damage than the lvl 70 druid that was in my party (No, not as a healer ;p). I haven't checked at level 70 yet, but I'm hoping i'll ding it soon and I'll see then.
As for our uses, there is always sap which is quite usefull (the better if you specced improved sap, which I have.). I pretty much "offtanked" every time I went to an instance so that might be usefull too.
Anyways, I don't think rogues will completely dissappear from raids. Atleast I hope they won't.