The COP of heat pumps at -30º isn't particularly great anyway, so you don't even necessarily need new technology, you just need to install inexpensive electric heat strips for when it's incapable of keeping up. In places with low emission electricity generation, that will still offer significant environmental benefits vs. gas.
Also, the good ones can modulate, so you can oversize them without any real penalty for efficiency. So if your heat loss at -25º is 35K BTUs and your heat pump can put out 80% of its capacity at -25º, then you could just get a 48K BTU unit. It will be oversized 90% of the time, but it can reduce its output when it's warmer out and still run efficiently. And the capital costs of upsizing aren't much at all; I know when I was looking at them, going from 2 tons to 3 tons was only about $1K more.
I do think people underestimate heat pumps' ability to perform in cold temperatures. The Fujitsu heat pumps I have in my house aren't even designed for super cold weather, but they can put out 100% of their rated capacity at -21º at a COP of 2.15.
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