My understanding is that this is not what the SFA are looking at. They want one place lock stock and barrel and do not want a mixture of venues. This leaves them the choice of Hampden, Celtic Park, Ibrox or Murrayfield. It's all or nothing. They are not looking at a mix and match solution.
If (and it's currently a big if) more than 20,000 SSC memberships are sold then qualifiers need to be at one of these above grounds as members are guaranteed a ticket. Once away supporters, corporates, press, hangers on are factored in there are probably only three football stadiums and one rugby venue that are suitable.
And they have to relocate the 100s of SFA and SPFL staff currently in Hampden. Oh, and a museum. RĀ£gan cannot afford to make an erse of this.