I haven't spent a dime yet, since I just got in a few days ago and still finding my footing. But when I go to draft, I can pay 5000g or 750gems to enter. If I go above 5 wins, I get more gems back than it costs me to enter. So even though *most* will not be able to draft free, for some people it should happen. 6 wins means you net 100gems more than you paid and you still get 40odd cards + 1-3 boosters. I haven't tried yet, because I dont have 5000g, or any gems at all. I'm just curious.
5 wins in Draft is significantly harder than you think. Or at least it will be eventually. Going infinite itself is going to be even harder than that.
The problem is that it's Best of One. This means mana flood/screw, going first vs going second, and other random factors have a significantly greater effect on your chances to do well. There's a reason that REAL drafting and sealed is Best of Three. And it's a very good reason. Best of Three lets good player's skill have enough of an effect on the game that they can somewhat mitigate all the draw RNG. Best of One is a cluster**** by comparison.
In addition, after the initial wave, I expect most of the people still drafting to be the best drafters on the platform. Just because those will be the people who can afford to keep going instead of playing once every 5 days, either due to actually going infinite (true drafting gods) or through a combination of going near-infinite with some money thrown in. When playing against the best opponents available, in a best of one format, it's going to be extremely hard to get 5 wins consistently over a long period of time. Draw RNG and just general hard opponents is going to make you lose enough that you won't go truly infinite. And THAT, THAT RIGHT THERE, is the problem.
This system is fine with something like Hearthstone where draw RNG is less important AND the mode rewards you the primary F2P currency AND the mode is possibly 2 days worth of grinding for a F2P entry after a 0-3 run.
In MTG: Arena, "near-infinite" isn't good enough. The mode rewards gems, and you don't have any other way to earn gems for free. So as soon as your total rewards dip below the 750 gems mark, you're done as a F2P player until you gather up 5000 more G to put into the system. This is going to utterly destroy a lot of F2P player's ability to fully enjoy the mode casually, because the only F2P players who will get to play lots of drafts will be those people with 10+ accounts where they do all the dailies every day and don't even touch the 4 wins bonus. Every couple of weeks they'll get to do like 10 drafts in a row and that's good enough. If you don't want to do something like that, this system just sucks and feels designed to either make you spend money or piss you off so much that you just quit the game because 1 Draft 5 days from now REALLY REALLY SUCKS, especially if you feel like RNG mattered more than anything you did.
Drafts should reward gold or drafts should cost a reasonable amount of f2p currency to enter. Otherwise it's not even pay to win. It's pay to play. The mode is fundamentally broken when it's designed to only let F2P players enter 6-8 times per entire month, instead of once every other day AT WORST. Most primary Arena players in HS manage to be that kind of player b/c their daily quest is usually enough, combined with their prize from the last run, to play something like 25 days out of 30. Those same people aren't going to play a draft mode where it's 6 days out of 30.