No guarantee he'll go - heck, no guarantee any of them will go. It's possible the situation will engender a siege mentality and group loyalty that keeps everyone. It's possible that guys like Mullan, Cannon, Goode (expiring contract) might welcome a move to the Midlands anyway. And yeah, in Hask's case, being captain will help.
But he won't be short of options. LI probably have salary cap space and have ambitions. Sarries probably wouldn't fit you're right, unless there's a surprising clear out coming - Quins I think are too tight to the salary cap to start drafting in big names from elsewhere.
But - if you're leaving London anyway, why not decide to go to a big 4 club, a club that really offers him a chance to fill up on silverware and boost his chances for more international places? I think he'd improve the 23 at both Saints and Leicester. Or maybe he'll decide that in a long term minded England set-up, his age makes hanging around post-World Cup pointless, and decide it's time to see the world again.
Lots of options. Lots of options for all of them - Varndell is another guy who'd get big bucks elsewhere and doesn't have an England career to protect, although he does have a Premiership tries record to grab.
Reading the Wasps forum, apparently the players weren't told - is that relevant to them suddenly putting in the worst and most disjointed performance of the season as the rumours started to break?