Sure, you can just go buy a certificate for an IP address. The Subject Alternative Name extension used to make X.509 certificates work on the Internet this century takes IP addresses (IPv4 or IPv6) just as happily as DNS names (including IDNs, written with A-labels) or email addresses. You will need to prove enduring control over the IP address, often by showing that one of the RIRs issued it to you as part of a block assignment.
Of course running an RIR isn't free, and so the RIRs charge fees to their members, Cloudflare will be paying APNIC (and probably all the other RIRs since they're a global company).
And we're straight back to the usual suspects insisting that surely they ought to be entitled to everything for free. How can it possibly cost money to blah blah blah. Basically all you need to watch out for with such people is to make sure you get paid up front, because given an opportunity to stiff you they won't even feel guilty.
Sure - but with most of the same caveats that apply to moving your own globally public IPv4 address around... ie, you need to register for an AS number, buy the IP space you want, and publish routes in the global internet routing table.
Its nowhere near as cheap as DNS and much more complicated (since you're concerned about things like how, physically, pulses on a wire/fiber will make it to the edge of your network.. you need to peer with one or more ISPs).
You could lease address space from an ISP and make all of that their problem, but then of course its not _your_ IP space. Think of it like the difference between being an internet user (leasing IP space) and a member of the internet (running your own network).
Since we're specifically talking about DNS in here though, I really don't think a stable IPv6 address would be a viable alternative to what we use DNS for.
Of course running an RIR isn't free, and so the RIRs charge fees to their members, Cloudflare will be paying APNIC (and probably all the other RIRs since they're a global company).
And we're straight back to the usual suspects insisting that surely they ought to be entitled to everything for free. How can it possibly cost money to blah blah blah. Basically all you need to watch out for with such people is to make sure you get paid up front, because given an opportunity to stiff you they won't even feel guilty.