Bottom line. If, under the 'old' system that I must have (possibly) played for two days I could have cleared my '6 games won' metric and obtained 2 keys, repeated that for 12 games and thus had four keys and, let's say 2 extra keys on the prestige progression in one hour and now and in future have to do twice as much for the same, then I'm worse off. If I do the same and get the same then I'm not.
To an extent I'm somewhat concerned by the fact that the "Journey system" is to become the norm and thus, from experience, the F2P part will involve a lot of time and often frustration. I'm unconvinced that the idea that every player will win roughly half their games as is expected - this applies across all levels of player, not just those at the top end - and when one of the quests is e.g. "Win 100 games with SK" when it gets matched against an opponent whose deck is (or appears to be) geared towards beating your deck easily (unless you want to take a net deck and just follow the instructions, but where's the fun in that? Especially for a casual player, like me, who plays for fun, not to "WIN, WIN, WIIIIIIIIIIIIIIIN!!!" - as it sometimes seems, so many others do) and this affects time spent and I, like I think a growing number of people, am somewhat fed up of the lovely things you can get for a 'reasonable price'. That is simply chasing an impossible end condition and is simply a way to obtain money or monetise (same thing) the game but which feels, to me, to be excessive. In short, the allure of the journey system will run out very quickly unless more 'goodies' are added as lures, and it is likely they will be. By clarification of that last sentence I mean that those who buy into this are those who buy into the 'shiny', or superficial, and also that while I am likely to purchase another journey as parts of it were fun at some point (and that will be sooner rather than later) it will become less so as I will have all the cards and then, if not before, the frustration(s) that I and others talk about on this forum will come to the fore more than they do now and they will then become more and more important than other things. Not all of us want to gain 'rank' and be 'pro', whatever that means.
Whether the above is a sustainable business model or not (e.g. it looks towards high burn/turnover rather than slower growth) is something that will have been considered and is, unfortunately, probably sufficiently good as an income creator to remain. I still think a better matchmaking system would be worth more in terms of making the game attractive. But I think it's fair to wait and see what the future holds and wait until others have appraised it and its value before jumping in.
*snip*, or I'll write another essay.