Just a few changes I had in mind that will allow blizzard to still fill their coffers but make the system much more accessible to new and returning players, as well as concurrent:

The rewards track is fine, double the gold earned or make it 150g so that every 2 is 3 packs earned.

Legendaries and Commons should be full dust refunds

Get rid of standard

Update both the classic set and older expansions to be more in line with how fast the game is now.

All uncraftable cards should be given to all players regardless of when they started playing. The tutorial should explain all key words and give you free card packs each time you finish. One mini game per keyword, and give the player a golden card pack, to ensure new players have a solid foundation to start collecting cards so they can win.

Updating older sets and classic combined with getting rid of standard will incentivize players to purchase packs from ALL expansions, I understand you have a business to run and it must be profitable, but you won't have a business if new players can't play without dropping at least $100, and older players are leaving in droves.