Not sure if it's dead, but there are sooo many of them, and they typically encapsulate someone else's idea of what leads to productivity. So, it's hard to find one that fits exactly how you'd like to work, and of the several I tried, there is always ONE big thing that keeps me from adopting it fully.

So, it's not dead, but it's a very crowded space, and discovery is a challenge. It's the classic red ocean. If you're going to build something, I'd spend the time elsewhere.