Back in November, I quit WoW despite the fact that it was the most fun I've had in WoW since vanilla (I'm a lore junkie, so completely new lore is an enticing thing for me) due to simply not being able to have the time to play nor the ability to afford playing. However, as of late I've been reading info on what's going on in 5.4 to see if there's anything interesting (Mostly because, from the sounds of it, the next patch is the one where players get to fight and hopefully kill Garrosh, which is something that interests me greatly).
That said, I've been considering coming back for 5.4 in order to experience the content I've missed. I need to ask, however, if there's been any new content introduced since November of 2012 that will be removed in 5.4. If there's going to be some major content I'm missing, I'd rather know now so I can weigh if I should get back in prior to 5.4 to try and see it all.
The big thing I can think of off the top of my head at this late hour is the content in the barrens that was added in 5.3. The content being removed that was added in 5.3 is: The quests involving Voljin and the re-taking of Sen'jin village, the taking of Razor Hill by the rebellion, the weekly quest to gather supplies for the rebellion, the quartermaster that has various vanity items and stuff on it and I believe the tokens that can be turned in for gear, not positive on that last part though. That's all horde side, I don't know what the alliance side stuff was. There may be more but I cant think of it atm, someone else may add stuff that I'm forgetting.
There is a small quest chain which illustrates the final rise of the Darkspear against Garrosh and the breakout of the war within the Horde. It is pretty neat, but not very long at all. If you are coming back anyways, just come back now though, as the patch will be released in about 2.5 weeks so this will give you a chance to do it & get a feat of strength from it.
The only things of note that will be removed are all the Battlefield: Barrens stuff, and Eternally in the Vale (along with various NPC's that perished, so certain quest hubs for the Golden Lotus are being removed).
I remember hearing that was being removed. I'm glad nothing from 5.1 or 5.2 is being removed, though. I may come back now, just to get that bit of content I'd otherwise miss. Sounds interesting enough.