I've seen the QF of the challenge cup been quoted. I think this is not a bad call, however there are a few practicalities that cannot be ignored.
The money from the extra fixture will be lost to all SL clubs.
The money for a full 2 days on sky would be lost.
Would 30k fans turn up for 2 quarter finals?
The practicalities of playing the CC QF at a stadium that's free. City would not have been available given that was the weekend they had their final premier league game.
Sky and the Beeb sharing camera and Tv crews, screens etc.
This years QF's
Wigan v Saints
Leeds v Leigh
Warrington v catalan
Huddersfield v London
Whilst Saints and Wigan would have brought their fair share at 15k. London and Catalan would bring close to nil, Huddersfield? Leigh?
You may get a decent turn out from Leeds and Warrington, but given Leeds lined up against Leigh I can't see it. The whole concept would be smaller and have less money. However the idea is not without merit and a smaller scale version could be done with the CC quarter finals regardless of MM staying or going, just at smaller stadia and on a Footy free weekend, closer to the semi's. DW could do it but so could say everton, Leeds, Birmingham with Aston Villa etc.