Depending on the they you mean, I could get behind this, but I don’t think Blizzard should be adding the “content.”
Vanilla was, in my mind at least, a place where problems were not solved by Blizzard changing game mechanics but rather the community of players coming up with unique solutions. The way certain guilds were run, the RP community, and a thriving addon development community really added a lot to this game that often goes unnoticed and forgotten, and is almost always undervalued and underestimated just how important it was to the success of Vanilla WoW.
Consider this post here. I think that Carespanker makes a great point about what “content” is, and what makes the game “content” great. It isn’t all on Blizzard. The key is the community of players.
So, consider that perhaps Blizzard not be the place where “more content” comes from in Classic. If Classic is as successful as I hope it will be, Blizzard won’t need to make more content.