For some reason decided to check about these earlier, a bit of an update:
sat imagery from 2010:

sat imagery from 2012:

So clearly they have gone somewhere.
This was the last update in the last thread about this:
daveymac82c wrote:
As I've learned from a friend of mine who lives in Mexico City, both B-25's are now in the hands of a team from the Mexican Air Force and will be restored to proper display condition.
As much as it would have been nice to acquire one of them, it's nice to see they are finally being taken care of. I can't wait to see how they look when they're all cleaned up and looking good.
Peace,
David
Any further information about this?