Once a new series is release, I think that the modern league only prioritize player with the newly released cards. If you don't buy the new summoners or cards from Arcana, you will be very in disadvantage against modern format players.
However, in Wild format, you will have the opportunity to play with all the cards available on the market.
There is going to be an article to announce the change in format after the release of Conclave. I hope it will not be too hard on Modern format player.
Thanks
