One of the biggest annoyances in MapleStory right now for me is the fact that I can't access ANYTHING on older characters due to this separate cash shop restriction. So, I have a possible solution.
Any character that has reached the age of 1 year, can share cash shop items with any other character that has reached the age of 1 year.
Maybe 1 year is pushing it, but the basic idea is solid. Nexon makes most of it's money these days off of cubes and characters. Most people make character in the initial period of when they're released their either continue them, or leave them. All money made is also in that initial period, and everything after that could be considered negligible.
So, with this in place older Maplers will have some sense of unity across the Cash Shops, and be happy while Nexon isn't hurt at all.
Nexon, I hope you see this and pass it off to someone for some thought, I'd really like to spend some money on this game but can't justifiy it when I can't even access what I purchase across 2 characters.