At the moment mythic titles and mounts are not removed (made unobtainable) when the next tier and massive nerfs to the previous one hit live servers. This leads to a situation in which titles are completely irrelevant and have no meaning. This is saddening. Especially since we already had a time in which a title meant a lot (you knew what was up when you saw someone with Death's Demise).
Also the mythic exclusive mount of the first tier should be removed as soon as the second tier hits (clefthoof of blackhand should have been removed when HFC launched) because let's be real Blackhand mythic is very very easy with 740+ (even with 710+). Again the mount has no meaning it should be reserved for the best PvE players (mythic raiders that do content when it's actually relevant). To offset this a little bit there should be a heroic exclusive mount (one drop per 10 players) and title to give motivation for pug and casual raiders as well.
Conclusion: Add title and mount for heroic BUT remove all titles/mounts associated with the current tier when the next one hits live servers in order to create meaningful rewards that stay over time.