Even though there’s still a lot of stuff to do in TBC, I think the grinding is built into activities and is less tedious/prone to fatigue.
Plus, 10/25 is way easier in terms of coordination/recruiting.
Add in the QOL and PvP being a more accessible feature, and I think it’s less likely to have a massive drop. All that said, though, I think every launch has attrition after the first month or so.
I’m optimistic that TBC will hold people’s attention longer.