1stly If a car is mapped VAGcom will pick this up no?
2ndly they would look to save money...its a business ;grin:
3rdly not all elements would be covered by remap warranty, that would be only engine running...nothing around drivetrain etc
4thly your right 
My understanding is:
With bluefin and some other remaps you can restore to the original map and the flash count is reset to zero.
They could call in the ECU experts and try to
prove that a remap was once, at some stage, on my car but why would they?
As I said earlier - those who don't like any sort of risk in life should not bother and enjoy their fantastic car as it is.
Personally, I think the risk is very small indeed.
If my turbo pops next week or my engine gets screwed then I go to VW (remap removed), then Superchips then my bank….