More than that, it's been done several times for people who wanted different things.
At first they say "I just want IPv4 addresses to have an equivalent in IPv6" so that's there, albeit largely useless except for some types of software.
Then it's "Oh, I should automatically get IPv6 addresses if I have IPv4". Did that, it's in 6to4, every IPv4-capable node has a /48 in 2002/16 for it to sub-allocate as it wishes, the IPv4 addressed node acts as router for the subnet, and an anycast address optionally provides a tunnelled route to the entire IPv6 space.
But now we get what people really want, what they really, really want. They want to be able to parley an IPv6 address (which they'll have billions of) to get an IPv4 address so they can continue using the IPv4 Internet after the crunch. This is mathematically impossible, and so, more so even than something which violates a law of physics, just wanting it really badly won't make it possible. But that won't stop them blaming the engineers who "failed" to do it for their woes.