Am I surprised that PM Harper is saying non to another Afghan mission? No. Can he change his mind on a random weekend like he did with the training mission? Absolument. But Harper has had enough of expending political capital for efforts that he does not control very well. He is very fond of repeating that the Afghanistan war of 2001 to present has lasted longer than the two World Wars combined.
And I am very fond of pointing out that that comparison is damned near meaningless since (a) Canada did not have troops in harm's way for all of that time--just 2002 and 2005-2011--so the math does not work; and (b) having nearly 3k soldiers deployed and reaching 160 KIA is nothing compared to Vimy, Dieppe, the average day on the Italian front in 1943-44, Market Garden, and so on.
Yes, the war in Afghanistan has been long, but it has only been intense for the small number of folks who went and are now back, facing a variety of challenges (PTSD, post concussion issues, loss of limbs, etc). For the country, just as is the case for the rest of NATO, the war really did not touch the populace in any way like WWI and WWII did.
The point about the clock is that this is a domestic concern--how long can a democratic public tolerate a war? That depends on a variety of factors--the perceived stakes, the pace of costs (casualties, money), the economy at the time, and ... leadership. Harper rarely stood in front of the mission and stopped doing that in 2008. So, he can blame the clock and he can blame the duration of the war, but he knows that he chose not to try to shape public opinion because it seemed to hard and because it got in the way of his dreams for a majority government.
I just find the whole "longer than World Wars" line to be deceptive and evasive. There are good reasons to pull out, there are better ways to express what the country's contributions have been.