What price today for the IPv4 / 24 block today?

I doubt that you see rules of use or loss. For several years, RIRs have considered IPv4 as "transitory". V6 as an alternative will work once enough people use it. Enough people will use it when there is an incentive strong enough to do it. At present, the only serious incentive to use it is of a financial nature, apart from not having enough IPv4, there is no compelling reason to use v6. By taking steps to release v4 and thus reduce the cost of the networks, I do not think that this is in the interest of the RIR. Even if they took steps to restrict the number of IP addresses, this could have a negative effect on the price – the effect of the PI's recovery by the RIR and having more resources to divest could be offset by making it much more difficult to obtain these IPs or their transfer. around them.

So, as long as you can buy what you need, all the action happens at the margin. As the price goes up, people will be a little more efficient in using the v4, or use the v6 when that is a real option. At some point, the price will be high enough to trigger the move to a larger scale of the v6, or enough people will use the v6 to avoid the inconvenience of not having the v4. Either of these situations is far from it.

As for the price, I would say that you should probably be $ 100 or more for each IP address before the hosting customers even consider making the v6 only for some of their services. Below, you will see that people understand how to use less IP, but I doubt that there will be much pressure to stop using them.

With regard to the use of the v6 to such an extent that people do not see any benefit in having v4 IP addresses, it is also far away. If you are hosting a website and only 5% of your users can access it via IPv4, you will probably want a v4 address – many websites pay a lot to drive traffic to their websites, losing 5% of your traffic when it can be avoided, it's not a choice that most people will make. Especially since hundreds of websites can be run on a single IP address, even at $ 100 per IP address, the cost of supporting version 4 of each website is very low.

So I think you have to reach a 95% absorption rate on the v6 or higher before you see the application drop in a serious way. And until demand drops, some companies are using the v4 more efficiently, but overall, more people and servers are connecting each day. The overall demand for v4 will increase until it breaks down. > 95% absorption of v6.