Hello everyone,
I work in the games industry and I think I have a pretty good grasp on how developers and publishers think. So if Wizards really changed their stance on a 'Digital Product for Beginners' (which I think they did, because of the announced open beta test) I like to imagine the following things for MtGA:

• The move to link your Magic Duels ID with your Wizards account makes me think that they want a unified system for the future. This very strongly hints at a cross-platform title, where you can access your collection from any device MtGA is released on, which will hopefully be all major platforms (PC, XB1, PS4, iOS, Android).
• It will most likely be F2P, seeing as pretty much all successful digital card games are as well. I can imagine the model being similar to Magic Duels... although this remains to be seen, if they want it to be a financial success and a real competitor to the other games (which for past games seemingly hasn't been the case).
• At first I thought the initial content would be the new Core 2019 core set (July 2018), but that would probably not work due to the beta test. Wizards likely wouldn't spoil all those cards that far in advance. So I'm guessing that there will be the Ixalan block and maybe even the Amonkhet block, depending on when the beta is going to start.
• The Magic Duels campaigns were well received, so I think there will be something similar for each released set on MtGA.
• There will likely be a format akin to Hearthstone's arena format (get it? because it's called MtG Arena). So draft, sealed or something like that. All major digital card games have this now, it would be a shameful oversight not to include this.
• 2HG (and probably multiplayer FFA) should be in, seeing as this is something that truly sets Magic apart from any other digital card game, which (afaik) are all 1on1 only.
• Wild guess on dates: Beta starting around Winter time (so December~January-ish) and release coincides with Core 2019.

 
Wishful thinking with low chances of it actually happening:

• Being able to transfer gold and collection over from Magic Duels
• Commander
• Planechase
• Archenemy
• Momir Basic

What do you guys think?