Rohit is more likely to be test class than Raina imo.
I think Subramaniam Badrinath should be in the India test team instead of Yuvraj for the immediate future but Ajinkya Rahane, Cheteshwar Pujara and Rohit Sharma are the long-term replacements for Dravid, Tendulkar and Laxman IMO.
I don't see Rohit as a test opener, even in the mould of Sehwag since Sehwag is a bit of a freak as a middle order player who can pwn opening batsmen with the new ball as easy as he did bowlers with an older ball.
Suresh Raina would, more than others, benefit from a county stint. He has some real issues which will hinder his success at test level. No doubt he can destroy attacks when the boundary is in but he has to learn how to play 4-day games outside of India where he will get short balls and the ball will swing.
He could, long-term, be the No.6. A blaster who also chips in with some useful spin but I don't see him any higher than that IAH plus Ravinder Jadeja, Kedar Jadhav, Sunny Sohal, Virat Kohli, Ameya Shrikhande and Manish Pandey will feel they can make the No.6 spot their own too in the future though some of those are too early into their FC career to even think about being an India test player..
As it stands, I see the XI as:
Gautam
Sehwag
Dravid
Tendulkar
Badrinath
Laxman
Dhoni
for now and long-term (ca 2012 onwards, no earlier and based on adapting to non-Indian conditions):
Mukund
Srivastava
Rahane
Pujara
Rohit
Raina (if he works on his short ball batting)
Karthik