There is no problem with looking after those with greatest loyalty first, just like all other clubs do. (And, sad to day, United are light years ahead of us with how they do this.) If you haven't got the loyalty, you don't get a ticket until those with loyalty have been sorted.
This does NOT create a closed shop. Each season, there will be hundreds of last season's fans who can no longer go, due to moving away, change of financial situation, other interests, death, etc., thus freeing up tickets for the next generation.
What creates the closed shop is that the club continues to allow those with loyalty to pass on their tickets for others to use. Stop that, and you end the closed shop, and a lot of the problems sort themselves out.
I was told by a senior manager that the obstacles to change come from powerful voices in SoS who rather like the current arrangements.