I have a direct interest in this proposal. Having got that out of the way, I generally agree with principal of the proposal. If a bunch of organisations want to bunch together and set up some common infrastructure for interconnection, this is probably more important than giving public ip to a tiny number of dial up end users. One suggestion:
Assignments will only be made to IXPs who have already applied for, or received an IPv6 assignment for their peering LAN.
This is pointless. You can't make people use IPv6 and politically stuffing it down the throat of an IXP won't do anything other than cause facepalming. It certainly won't cause ipv6 to be more rapidly deployed. Either IPv6 will happen because of necessity or it won't. If IXP participants want ipv6, then they will push the exchange operator to implement it, and it will be done. But mandating an ipv6 assignment request in an ipv4 assignment policy is, well, silly. Also, a nit:
This space will be used to run an Internet Exchange Point peering LAN, other uses are forbidden.
The comma should be replaced with either a semicolon or else a full stop. Nick