Unless the said prospective investors are hardcore green supporters, it shouldn't faze them from investing. People still use inefficient cars, still throw trash everywhere, and some don't even believe that pollution can impact the global climate. They're going to look at one thing only, and that's their bottom line.

What it could affect though, are governmental regulations. If this starts getting some real traction, it could turn into a demolition job by the media and green groups. That could throw off potential investors.

As for solutions, miners could start using renewable energy, which some are already doing. Bitcoin could also do away with PoW, though I can't really propose any alternatives.