Hextech Crafting with all content owned

So Riot has already told us that you can get skins and champs you already own through chests, but you are supposed to be guaranteed unowned content when you reroll 3 items. So I've used my PBE account to see what happens when you own all content possible in the game. I have spent HOURS buying every single skin in the store, every ward skin, bundles, chromas, even as far as all runes in the game (although last few categories are not impacted by mystery skins/hextech crafting) and here's what happens after that in case you ever wondered. The mystery skin option in the store disappears after you unlock all possible legacy skins. Hextech crates will obviously give the same drops, BUT, when you reroll skins you eventually stop unlocking new legacy skins, and start earning "permanent skin shards" which are gold bordered skin shards that are permanent unlocks but you already own them all. After i reached this point I did further testing with 150 more crates and rerolled all skins and every single skin was an "in-store" skin already owned. So if you are insane and bought every piece of purchasable content in the game, you can use crafting to get a LOT of really epic legacy skins, until you own everything except limited edition skins.