Two thoughts on this:
1) Today's coins are JUNK. Here in the US, the coin designs have been absolutely terrible. The State Quarters were semi-cool, but most patterns were too busy to be readable. Way too much stuff jammed into a small space. The 'shield' penny is a joke; it could've been designed by a 1st grader, and the new nickels are pretty bad too. Conclusion: the last good coin design was the Bicentennial Quarter. Almost everything clad is worth no more than face value, and unlike silver and 100% copper today's coins come out of the ground all tarnished and chipped and crappy-looking.
In other words, NO BIG LOSS.
2) My other thought is that one day, hopefully soon, someone will come up with a detector that goes significantly deeper. Imagine a detector that could accurately pick out coins up to two feet deep. This would essentially open up ALL PAST PERMISSIONS to be re-searched; every single inch of ground could yield amazing vintage coins, and because of the extra depth the coins would be VERY OLD on average.
To me, #2 is an exciting possibility that I'd like to see happen in my lifetime. Just imagine going back to all your best 'picked over' spots and cashing in on all the stuff you waltzed right over with even the best metal detectors of today.
A cashless future is inevitable. But as detectorists? We're looking for history. Today's zincoln-lincolns aren't history. Heck, they're barely even coins as far as I'm concerned.
'Nuff said!