This seems like a bit of a bungled announcement to me...
Let's say you're on PC. You already have an option for Magic that grants you full access to all of the game's sets, full rule sets, drafts, sealed, pauper, etc., as well as competitive play integration. The only thing it really lacks is a more stable client that looks better.
Arena gives you the flashier looking option...and likely better streaming options. But otherwise, it's a far slimmer package.
Let's say you're on console or Mac. You have never had a game of Magic that actually plays like Magic. There's always been limitations on the card counts, what cards are available within a specific format, etc. Sealed had a very limited version introduced once, draft has been completely MIA.
So, if this game had been announced as "coming to PC, Mac, PS4, Xbox One and Switch soon" I think the takeaway from most people would be "finally, I can play Standard, draft and sealed in the current format on my platform of choice!" Instead, it's mostly MTGO players scratching their heads.
Granted, I do think this is coming to all consoles and maybe Mac eventually...but just for optics, it would've been better to announce that right away to start the conversation off right.
(My gut instinct is they are hoping this will slowly take over MTGO, they just can't rip the bandaid off because of the intense financial contributions people have made into that client already...and it'd probably take years to slowly introduce all of the cards that format has).