Zero, not the Punctuation one, started a blog, and posted an interesting idea for WoW henchmen: What if Blizzard not only added them, but also made them programmable, like the Gambit system in Final Fantasy XII? Basically there would be building blocks for small AI programms, blocks like "if I'm under 50% health" and "cast healing on me", which put together would tell the henchman NPC what to do.
Of course that would be another big step towards World of Warcraft's solofication. But the henchmen shouldn't be so good that you could do heroics with them, so for most people the choice is doing normal dungeons with henchmen or not at all, because for many of them there are no groups to be found. So I do think that henchmen would be a good way to revive old group content, and to give players some ideas about group play much earlier on in their career.