I had a similar conversation with my frothing-at-the-mouth FD this morning, after 10% of our PC base had died since yesterday, and users were sitting down twiddling their thumbs.
First I reminded him that the documented 2014 budget proposal that I submitted last year had covered replacing all XP machines by April, but that the expenditure was overruled because I was told that nothing bad would suddenly happen that could kill all of our XP machines at once.
Then I again reminded him that my justification when questioned before the board, over removing all XP machines was that once the official support date has passed, it would only take a single untested software update to kill all our identical machines (at which I used identical twins as an analogy, and how genetically an affliction that kills one twin, usually kills another twin unless the other twin seeks treatment straight away (I also discussed virus outbreaks at the same time)), I also pointed out that once the official support date had passed, it would be unlikely that software manufacturers would test new releases of software against XP, and that I joked that the cynical would suggest that MS would deliberatly build in obsolesence to XP so that it died shortly after support expired.
Luckily for me all said meetings are minuted and right now the board are pointing fingers at each other, rather than me.
Personally I believe that what happenned yesterday was a result of MS not testing against XP, or inadvertantly releasing a non-XP update for XP, because it's not MS policy to test anything against XP.
Considering that today has been a total arse for me and my department, I feel strangely liberated, smug and awesome!!!!