Hello Mr Xteven,
I don't know what your plans are for genesys rated. But since that format is going to get more lists in general, could you not reset everything to 100 each list? And instead maybe just cut 500 rating from every player above 600 and reset the rest to 100?
Or you can decide the number, or another system, anything that doesn't make it so that the matchmaking is messed and you have to go through 86 boring duels to get back to having decent matches. Often against exodia decks that play alone for 15 minutes then quit when the deck's draw power ends, or similar.
Please,
Thank you,
Love you