Now let say this miner id is not just the address, but an ip/address pair. Each time a new node appear on the network it register itself on the network, and put on the global list of miners id, each time a new block arrive this address/Ip pair is hashed with the new block signature and miners id sorted on this hash, and the first 60 are selected for the next block.
The Ip will be used to send the work to the miner and to send it to the next so Ip can checked in and out even if that wouldnt prevent 3 ips to collude to steal work.
It could be made stronger if all nodes do traceroute on miners and a consensus can be reached on topography of ips, i tend to think its a problem that has a degree of byzantine fault tolerance as any node can check the traceroute of other nodes and deduce if the traceroute sent by another node is incohérent, i think its a classic problem of graph theory with a byzantine fault tolerance, similar to this Techniques for Detection of Malicious Packet Drops in Networks , taking in account that the topography doesn't have to be 100% accurate, but at least give sufficient probability that two nodes are not located too close to each others, and using some connectivity testing along path with a technique similar to the link. Some 'hard' consensus could be added if there is too much conflict above the byzantine fault tolerance of the system.
Would be a long shot, but wouldnt this garantee a certain degree of decentralisation ?
There are so many problems with this I don't even know where to start.
1. This scheme fails to provide the most important property: consensus. What happens if a node receives two different blocks, each with a correct set of 60 signatures? Which version of the blockchain is it going to choose? Note that this doesn't have to be malicious, it can be simply caused by a temporary network split.
2. You failed to explain what happens if one of the 60 selected miners doesn't respond, either maliciously or due to simply being offline.
3. Using IP addresses is a can of worms you don't want to open, trust me. Are you going to limit 1 unique address per IP address? Are you aware that sometimes thousands of people share the same external IP? Are you aware that network routing changes rapidly, sometimes several times per day? Do you know that a billion of IPv6 addresses can be rented for less than $1 per month? Have you thought about the privacy implications of linking coin addresses with physical network addresses?