No - I can't see them putting their Top 10 guys forward for this. In order for any brand to survive in the long term they need to give the lower card men a leg up from time to time. The Rumble often does this.
There are a dozen or so ECW listed Extremists (won't be called this for much longer) who don't get TV time due to time constraints.
There is every chance we'll see Stevie Richards pop back out, maybe even Terry Funk (as he's been associated with every other match too).
IMO this 06/07 year is all about history - about looking back on past WWF/WWE/ECW/WCW history so why not give some of the ECW men a shot?
Vince/Melina fired Mick Foley but Heyman could just as easily ask him back. Would lead to some nice Flair - Foley angles, which Flair might welcome given his choice of Tag partner (Piper) is out long term.
RR is less about raw skill, it's more about stamina, durability, sheer aggression. Choosing the right wrestlers for this is key for ECW. If they were to put too many 'storyline wrestlers' in there then they'd merely face off against each other and you'd get the more experienced WWE PPV wrestlers like HBK/HHH etc picking their easy targets and shortening their own odds.
The ECW men would need to last as long as possible. You could get Funk LEADING ECW as a team whereby they try and get one of their guys further along...
However until it gets closer to the date I can't see how it might truely pan out.