> The new players would each get a /24 and everyone would say that's "enough".

From where?

All then-existing IPv4 addresses would get all the bits behind them. There would, at the time, still be IPv4 addresses available that could be given out, and as people got them they would also get the extend "IPv4x" address associated with them.

But at some point IPv4 addresses would all be allocated… along with all the extended addresses 'behind' them.

Then what?

The extended IPv4x addresses are attached to the legacy IPv4 addressed they are 'prefixed' by, so once the legacy bits are assigned, so are the new bits. If someone comes along post-legacy-IPv4 exhaustion, where do new addresses come from?

You're in the exact same situation as we are now: legacy code is stuck with 32-bit-only addresses, new code is >32-bits… just like with IPv6. Great you managed to purchase/rent a legacy address range… but you still need a translation box for non-updated code… like with CG-NAT and IPv6.

▲

wmf 2 hours ago | parent [-]

ISPs can still get /24 of IPv4 today for free even after it "ran out". This comes from space that was set aside before runout. https://www.arin.net/participate/policy/nrpm/#4-10-dedicated...

This IPv4x thing is bullshit but we should be accurate about how it would play out.

	▲	throw0101d an hour ago \| parent [-]
		So under this IPv4x proposal one gets an IPv4 /24, and receives a whole bunch of extended address space 'for free'. But right now you can get an IPv4 /24 (as you say), but you can get an IPv6 allocation 'for free' as we speak. In both cases legacy code cannot use the new address space; you have to: * update the IP stack (like with IPv6) * tell applications about new DNS records (like IPv6) * set up translation layers for legacy-only code to reach extended-only destination (like IPv6 with DNS64/NAT64, CLAT, etc) You're updating the exact same code paths in both the IPv4x and IPv6 scenarios: dual-stack, DNS, socket address structures, dealing with legacy-only code that is never touched to deal with the larger address space.