One of your best intro's yet man ... I was close to ROFLing for real.
A few quick points.
#1. End of expansion burnout is ALWAYS bad. The only time it wasn't strictly terrible was in vanilla and then it was only because we really didn't understand how much content turnover there was (or at least my guild didn't until very late). The only reason why BC didn't experience a major lull was because of the content nerfs that came in and opened up content that was largely unreachable by the majority ... essentially opening up new content in the 11th hour. Obviously WoTLK's year of nothing sucked too.
#2. This was the worst expansion ever and Dragonsoul one of the worst real raid tiers (I'd have to say Naxx v 2.0 and ToC were worse). What made it worse was Dragonsoul followed an already lean (but high quality) raid in Firelands. Ultimately this entire expansion was super thin on content and people just ran out of things to do. Therefore this end of expansion is already double stacked in the wrong way.
#3. LFR made the content even thinner. Many players in my guild burned themselves out on DS by raiding it on all their alts ... theres only so many times you can look at the same encounter before it loses any and all meaning to you. Yes I know this was their own fault but that doesn't change the fact that it happened to many people (thankfully I never did this)
All of that makes this end of expansion significantly worse than any other one. In the end I believe WoW's end of expansion design
(turn over all content, essentially making everything done before worthless) is somewhat flawed. I understand why they do it (it's far easier than anything else) ... but I believe they have the creativity and skill to essentially remodel the end of expansion design such that not everything is completely invalidated and therefore leading to ultra-burnout for everyone who ever raids/plays for character progression.