As long as they broadcast it free to air on all platforms, technically anyone could bid for Euro 2012. By the time the Championships air only Kent will still have to switch over, meaning any broadcaster on every platform will have the required 95% of the audience anyway, although I think the figure is already in the 90s anyway.
Even Sky could pick it up. It hardly fits their business model, but it would be interesting. They'd get to brand it, use the whole championship to promote their products and crucially get it off the BBC and ITV and plus they would get loads of ad revenue, which would pay for it itself. They'd could just chuck PickTV, PickTV+1 off Freeview and create 'Sky Sports Euro 1' and 'Sky Sports Euro 2'.
Unlikely, but I wouldn't put something like that past BSkyB.