I would implore Blizzard to do this for Content like Legion Assaults first off and Hopefully Expand the Follower Dungeons all the down to Classic>Current so a Person can just level with Bots if they want too. Even AI Bots for Previous Expansion Raids that have not been Nerfed as soon as that expansion becomes Irrellivent which is basically Day one of the New Expansion therefor that Previous Expansion and all Subsequent ones be made to be done Solo as in No Mechanics that affect an attempt and fi players want to do so and are still levellingand want to do a Raid say Hellfire Citadel then you can head to your Garrison and either do LFR or Normal Raids for Each Expansion and are either paired with 9-24 Bots or if you have friends or guild mates who want to Experience the Older raids if they Joined WoW well after those Expansions came out.
I know this Wont ever Happen because Innovation is not a thing Blizzard does very well. One Example of them failing a Feature that would of worked Game Wide if implemented like it was initially was the Item Scrapper but we never got it and Never will due to the Close Minded Think tank that is Blizzard and Co.