In light of the new subscription model, it would be nice to see a tiered system to fit everybody's requirements, this would open up the available options to more people.
Free - you get the base game plus bug fixes and patches
DLC - You get the free version with the option to purchase additional content (such as Map Packs/Songs or new environments etc.)
Subscription - You get all the content at a fixed monthly cost.
LifeTime Membership - You pay a one off fee and get lifetime subscription at no additional cost.