I honestly don't know, HuskyPup. I was first contacted by a Rep about 4 years ago and always assumed it was because I had hit a certain level in revenue. But when I was last contacted it was with a genuine, personalised email rather than a generic one like this. I used to work quite closely with my advisor and his successor, and respected their advice (although I did subsequently spend weeks working round the clock to undo many of the changes they had suggested given the ATF Page Layout Algorithm).
My second advisor left the firm. And when I dropped Adsense below the fold, my income from the Adsense units dropped so significantly that I assumed I fell off their radar.
The email is totally generic. For example, part of the consultation on offer is an "Introduction into other monetisation solutions from Google, for example AdMob and DoubleClick for Publishers" - and I've been using the latter for at least 2 years.
Incidentally, I've tried to book an appointment for after 4th March 2015 but the calendar doesn't go any further than that. Perhaps Google is calling the "end of the world" and after 4th March 2015 it won't matter any more, anyway!