I recognize that Mark will almost certainly follow through with his original Pricing Changes, but I'm opposed to it alone (without adding Samuel's proposal or other mitigations).
I didn't think I had.
So, what do you mean by "member payment tied to a specific group or groups"? I'm not aware that such a thing is under consideration.
As I understand it the only payments tied to specific groups are in Mark's original Pricing Changes: the base fee for Premium and Enterprise groups, plust the per-member fees charged to those groups above the base number of members. But those are payments made by the group, not the member.
Samuel's proposal (this Topic) is that fees paid directly to Groups.io by the member will be for membership "at large" - the user with a paid account can join any number of groups irrespective of that group's available "free slots".