Every once in a while I wonder about the future of metal detecting -- surely someday the technology will exist to "see through dirt" -- or at least a 3D MRI of sorts.
With today's technology (in almost every smartphone), between GPS, electronic compass, and the accelerometers and gyroscopes in tiny microchips, it's possible for a detector or know "exactly" where it is, and add up the data from multiple passes over an area, and build a map of what's down there. Not a "picture", but a grid of target IDs. Then you can zoom in and out on any area you've swept. The more you sweep a spot, the more data it has to identify what's in that spot. Foolproof? No way, but one more incremental advancement in the hobby.
I don't expect to see images of buried objects in my lifetime-- hells bells think of the resolution needed to tell a coin from a bottle cap, even if you can "see" its outline. Maybe someday the Fisher MRI2051 will outperform the Garrett CatScan2049, but neither one will be able to tell a ring from a pulltab missing it's beavertail. LOL keep digging it all!