25 man guilds are indeed becoming far and few between, I personally enjoy 25 man raiding and am part of the last 25 man guild in our server. We are 2/8 on heroic 25m DS, if we split into 2 or 3 10 man's we could probably already be 3 or 4/8 due to having less logistics and having to manage less people in a raid but we simply enjoy 25 man's over the 10 man versions of raids.

The only issue I have with 25 man raiding is the disproportion of tanks compared to 10 mans. 10 mans need 2 tanks yet 25 mans which have more than DOUBLE the amount of people only require 2 tanks as well.

Whilst I agree 25 mans are on the way out bar some diehards, I disagree with the reasoning of the author.
The 'maze' analogy is particularly wrong. Its not about how complex it is, its the fact you have to ORGANISE 10 ppl or 25 ppl to do it simutaneously. Thats not the same thing AT ALL. The rewards are SLIGHTLY (and by that i mean so slight its negligable) better for 25 man, but that is NOT worth the extra hasstle and burnout the RL/organiser goes through. That said there are examples of 25 man being easier (ie one death does not mean autowipe etc), but again it is not worth the hassle of the organisational difficulties. So basically we are saying 10 man is easier to organise, so its quicker and more FUN in a GAME to do. See my point?
Keep 25 mans sure, some people prefer them, and fair play to them, I wish them all the luck in the world, but I prefer a quicker easier game (organisational wise at least) for FUN, rather than making it another logistic problem I have to solve before we can start killing anything.