I still think we need separate leagues and your league is your choice (assuming you qualify for the league) and ranking system gets adapted to better indicate skill.

I think people may even play more and buy more because they may have an account in each league. Or they have one account that they try in gold and silver. But of course they cant get the rewards from both leagues but they can see how they match up.

Each league could have 3-5 levels of play giving it a continued feel of improvement and a bit of the grind.
And so top level people usually get to play other top level players assuming there is a match up at that moment but you could end up against lower players.

And then none of this manipulation of where you tend to get more points on average than you loose. Go back to a regular elo that attempts to properly rank skill. A bad player or bad bot would be rated low. I feel like the system right now makes even a terrible silver player able to hit diamond. Therefore our system plainly does not have an elo that is interested in ranking skill. But we would do well to have a ranking system that ranks skill for each group of users meaning those who just started with a few cards. Top players who can spend low hundreds. Those who spend high hundreds then those who spend thousands and then the pro/top levels.

In fact @yabapmatt and @aggroed should consider an invite only pro league where top next level players get invited and the lowest pro level players may have to move down to diamond if they are the lowest players in the pro/master league.

However your ideas for varied rewards based on levels works well. But a user should make a real decision... do I try to play diamond league where rewards are much higher but competition is much more difficult. Maybe get a top 50 rank... or go for Gold league and try to get top 10 ranking.