In the last 20 years, there were only 5 dominant PR champs in my opinion. Dominant in the sense that when they won, they won with minutes, and they won because they accelerated where they wanted, and they were in the game for several editions, not just one good show:
Ballerini, Tafi, Museeuw, Boonen and Cancellara.
The only realistic chances for finishing first in Roubaix are for Vanmarcke, Gaudin, Turgot, Boonen, Cancellara, or Van Avermaet.
From all the nominees, only Vanmarcke can be considered as relatively 'new'.
As both Boonen and Cancellara are still competing and going for their 4th or 5th win, nobody of the outsiders will be allowed to win. And so Stybar will only win if Boonen has a problem, or if it will be a tactical race.
So forget it for the win, a 'new' rider will only be in the top 10, not even in the top 3 this year. Maybe Boom, Hushovd, Langeveld, Chavanel or Haussler can have a super day and finish top 5.