US hasn't but some countries have specifically reduced or removed nickel use in their coinage because of health concerns. Canada's reducing, but for weight reasons. Sweden did so for health concerns. There's some drama over the relatively high content in 1euro 2euro coins, but no change for now. There are regulations for jewelry and other items in close contact with the skin. There are a lot of women out there having some womenly medical devices replaced because of nickel content as well.
Here's where I'm at, for me, personally,
Some people are sensitive to nickel, on the outer skin it can cause pretty bad rash. Not sure what it does to the innards but not good if you are sensitive. Sensitivity to nickel can develop, just because you are not sensitive today does not mean you won't become sensitive (so if some symptons develop down the road keep that in mind). There are other concerns but those may be compound specific and as Rosumm correctly enlightened me, do not appear to be vastly different kinds of concerns than I should also be evaluating with kanthal A1 (which is what I'm using today).
I've been handling nickel coins, eating food, drinking water, touching dirt, breathing...and a lot of other ways have come into contact with nickel, all my life and don't know of a specific concern for me. Since I've done some research I know to keep my eye out. If I get a rash, no biggie stop touching the nickel, I'll know what the issue is and the rash will go away. I'd like to see something that makes me more confident that nickel won't be in the vape I'm inhaling... Or if there is some, what are the levels. Hard to believe there won't be some.
The other side of the coin is the prevention of dry hits...that always worried me but still took that dripper pretty dry when I was about to switch up flavors. There's clearly a reduction of harm there.
I'm excited about the technology and will likely adopt. I'll keep my eye on nickel info, hope evolv shares what they have, hope more studies are done. If I have any reaction, or notice anything different throat / lungs, well then back to kanthal and I'll still love my sweet new mod. 10 bux more for 10 watts more, a couple other new bells, and a temp feature I ended up not using won't be too bad. If all goes well, then it's a great feature. Wonder if it can be accomplished in other ways as well and if those other ways could be as accurate or more so.