The IPv6 address space covers the IPv4 address space already: https://en.wikipedia.org/wiki/IPv6_address#Representation
> During the transition of the Internet from IPv4 to IPv6, it is typical to operate in a mixed addressing environment. For such use cases, a special notation has been introduced, which expresses IPv4-mapped and IPv4-compatible IPv6 addresses by writing the least-significant 32 bits of an address in the familiar IPv4 dot-decimal notation, whereas all preceding ones are written in IPv6 format. For example, the IPv4-mapped IPv6 address ::ffff:c000:0280 is written as ::ffff:192.0.2.128, thus expressing clearly the original IPv4 address that was mapped to IPv6.
That needs some sort of gateway to work, but I'm assuming that that is the kind of thing your ISP would do for you.
And if you have to convert each IPv4 only host to an IPv10 host to use it, why not convert it to dual stack IPv4/IPv6 instead?