Lead ingestion by waterfowl has yet to be proven by an actual scientific examination. That report done years ago was debunked simply because there was no serious forensic analysis to prove lead was the killer. And because of that, we still see that lie perpetuated in the press and now repeated among shooters.
I give more credence to reloaders using closed lids on case polishers and requiring high rate ventilation of indoor ranges. Airborne lead is quite a bit more ingestible than a lead shot picked up off the marsh bottoms as gullet grinders. As for copper - well, the auto industry is seeing a change in brake pad materials as the EPA and DOT are requiring it's elimination. That is why we see "ceramic" pads coming out - and by test, they are actually softer, wear out sooner, and offer less braking as a result of the loss of copper in the mix. Not what some would tell you over the back yard fence, but why would they know? Copper is a known toxic element, the brass grommets in field gear are considered a low grade haz mat, and it's also a common practice in roofing to install a copper wire down the ridgeline of shingle roofs to kill mold off so that it won't discolor them.
Given enough time I think we will see a change from copper to some other element with a high density simply because it will be cheaper and incrementally less toxic. If copper - why not powered steel? Seems shotgunners have shown it works acceptably well. We've seen the results of how fast steel jacketed bullets wear barrels, and the cost savings in cheap ammo can offset the marginally higher wear rate. Barrels wear out anyway - do we really need to use copper in the jacket to incrementally reduce it? Considering it's the leade exposed to the initial flame of ignition that does the most damage, especially on high round count weapons in full auto use, we really have other problems to work on.
Powered copper/polymer bullets may have a life on indoor range use, reducing lead exposure, but the shooting community will likely accept them only if they get performance on par with hollow points in the field - at a competitive price. We collectively think that a molded bullet should be cheaper than a jacket drawn repeatedly and then bonded to a core. Overcome that and they may become a significant part of the market.