One thing that always seemed like a big issue with Yugioh was the sheer lack of choice the players have in how the game is played. There are only two formats that are really relevant, and that's Advanced and Battle Pack Draft.
It would be an extremely interesting change of pace if we had two Advanced Formats. Imagine if the April 1 format was split between two brand new choices:
--a "Relaxed" Advanced Format list, wherein the current list would be changed to relax a number of its current restrictions (ex. cards generally going up, from 0 to 1, 1 to 2, etc.)
--a "Restricted" Advanced Format list, with basically the opposite happening and stronger restrictions placed on a number of cards.
A YCS held under this system would essentially have two tournaments going on at the same time; one for each format. (Of course, in an ideal world I would do away with the drafting portion of the tournament too, but I digress.)
I just think it'd be a really nice breath of fresh air to give the players the option of what format they want to play in - people are often not happy with how the banlist turns out, and this would give you a small measure of choice in how you want it to be. In particular, it would definitely be interesting to see which format turns out to be the battleground of choice for well-known players.
In any case, this probably won't ever happen, but it'd definitely be nice to see.