Kamsky’s line has been reasonably popular, with several high rated players taking it up on at least a semi-regular basis. I’ve fooled around with it myself (clearly not one of the high rated players I was referring to), although not with the early …Bf5 ala Kamsky.
These lines can often resemble Caro-Kann and Center Counter defenses - lots of similar themes.
I can’t recall any 2700 player trotting out the Alekhine in recent memory, especially against another 2700. Doesn’t mean one doesn’t exist, though. 
Randy, that’s why your rating is a whole lot higher than mine!
Fischer-Spassky!
As I wasn’t even conceived when those games were played, I’m allowed to not remember them. 
Two incredible games with the Alekhine in that match:
How about Topolov-Carlson (that would be Magnus), Linares 2008? 0-1 in 44.
That game escaped my failing memory. Armed with a database now, i can look at this more closely.
Carlsen has played it all of 4 times in classical events. His score is +1 -2 =1. Prior to the Topalov game you mention, he hadn’t played it in a serious game in 4 years (and he was rated under 2400 then). And he has apparently not played it since.
The larger point was that most 2700s, facing e4, are not playing the Alekhine. I imagine Grischuk wasn’t expecting it…and I can’t find where Kamsky has played it before.
So it seems the Alekhine is a very infrequent visitor at the highest levels, which was my poorly articulated original point in this thread.