There are not that many two letter codes (a comment said 26*26= 676) and they are reserved for country codes. Global tlds are three letters and up (eg com org etc)
ICANN will act in whatever manner causes them the least trouble, which will be to retain the status quo. They have absolutely no incentive to behave otherwise.
It's pretty detrimental to relationships when one side pre-declares their rules and policies, and then arbitrarily decides to ignore them.
I'd say they have a lot of incentive to behave in whatever way their published policies state, regardless of the impact to users of the cctld.
(I don't know what the policies are)