So as far as avatars go, there will pretty much be:
Robloxian 1.0 R6 (Classic)
Robloxian 1.0 R15
Robloxian 2.0 R6
Robloxian 2.0 R15
Robloxian 3.0 R6
Robloxian 3.0 R15
It's not bad- There's a R6 and R15 version per each.
And developers can choose to allow only one type anyway.
And users can choose to be one or the other.
So it's not really complex at all.