Some additions:
S-Tier
A-Tier
- RevTT (RTT) - Scene/General
B-Tier
- Cinemageddon (CG) - Movies
- Karagarga (KG) - Movies
C-Tier
- Metal.Iplay (RMT) - Music
- Pedro's (P*) - Music
- Exigo (E*) - Music
- LzTr - Music
D-Tier (Avoid)
- IPTorrents (IPT) - General (why?)
In short, Wayland is a protocol for graphics.
It's somewhat similar to X, as its main purpose is the same, however the archivecture is very different, and Wayland is much simpler/barebone.
If X is going to die or not — only time will tell. For now it can be considered another competing standard.