I've got it figured out. Remove character levels and gear stats. I know, sounds crazy right? Well then, let me explain.
Everyone interested in buying a boost is willing to do so because they hate leveling. Others who love leveling, may be getting tired of the linear content and design. I say, SANDBOX. Are you a new character? Would you rather jump right into current content? Perfect. Head for the new zone, and do some questing to get your experience. Once you are comfortable with your class, and each of your spells, go see your local Itemizer. The Itemizer will tell you which items in your gear can be socketed, and gemmed, which can be enchanted, and which can be enhanced with additional armor.
Everything works on base stats. You, mobs, bosses. The only thing that changes is the number. If a mob has a number on it, that it the number of characters it actually takes to defeat it. If you enter in normal mode, it requires 10. In Heroic, 25. In Flex, the number will scale to meet the size of your group and the boss' power adjusts accordingly. Depending on your modifications only will determine how likely you are to succeed when working as a team.
Dungeon difficulty will adjust from 1-5 in normal and heroic mode. Of course, a 3 person heroic will be more technical than a 3 person normal. A solo dungeon will still pose a challenge, but NPCs will not be elites in normal dungeons, thus removing their more difficult rating. This means you can still solo older content in dungeons and raids for transmogs and they will scale to hit your level, or slightly above for a challenge.
This is the same as scaling content to match lvl 90s in Elwynn or lvl 1s in Pandaria. Every bit of the technical difficulty would still exist, but in this sandbox environment, you could go anywhere, do anything, quest with anyone. Experience bars would be converted to wisdom bars. The more content you complete, the more wisdom you gain. Wisdom is then converted to currency and provides you access to things you would have previously purchased with HP/JP/VP/CP.
You would still have to earn the gold to pay for respeccing, for flying, for itemizing. Professions would remain unchanged as would classes. You would still have to go to outlands to get cloth to level First Aid, or go to Dalaran for your JC Dailies. The only thing we are doing is changing the order in which you do things. You wanna start in Northrend and end in Silithus? Go for it. This sandbox element would make the content feel far different than it had in the past.
For those who just want to farm an area (ex - 90s farming rep at Timbermaw hold with 1 shotting mobs), you can simply toggle your wisdom to 5x. This means you hit 5 times harder than you normally do while content is scaled. Once you leave that zone, you are reverted back to normal. It may just be me, but something like THIS would keep me from buying a boost to 90 and allow me to jump right in wherever I like.
*** Please note: This is just my opinion. It was a random idea I had in response as to why I would rather purchase a boost to 90 than to quest for 90 levels. For me, this sounded like an alternative. Now, is it practical or probable for WoW? No. Will it ever be implemented? No. Am I asking for it to be implemented? No. Do I need to go find another game to play? No. I am very happy with WoW and love the end game content. Again, this was more of a pondered response to another thread. If you are a Lore Knight and are taking this thread too seriously, please find the nearest exit. I am happy to discuss opinions, but I will not argue with fanatics. ***