Whereas my proposed system would eliminate the need to validate all the blocks until the genesis one and will only need to validate blocks until second genesis block/genesis block after archival whatever we name it.
You can achieve something very similar even without modifying a single line of Bitcoin's code: Simply download an archived blockchain copy - this is much faster than validating it - and then prune it. (There seem to be even services for that: getbitcoinblockchain DOT com - dunno if it's trustworthy so I disabled the "hot" link).
You node then would not contribute to the validation of the early parts of the blockchain (in your system, you wouldn't either). However, it still would be better than a SPV node because it would validate everything after the point where you downloaded the copy.
It should even be possible to download already pruned archived blockchains (I haven't found a download repo however). You can also create a tool for distribution of these blockchain copies using a network like BitTorrent, although you will probably never be 100% secure that you have a "clean" blockchain copy.