I wasted 2000 CP a few hours ago in hopes to get a cowboy dogi, no luck, no boxes, no dogiballs, so in a way I understand where are you coming from. Removing pay 2 win is a very good step, but replacing it with Gambling is a big no-no in my opinion, but hey, there are no perfect solutions.
It would be very smart to implement a system where you can get "limited offers" in cash shop, like, 10 brown boxes for 100 cash points, available once per week, it would limit the amount you can get, and not many people will spam making new accounts and cash on it, in order to get advantage.
Yet, you have to keep in mind that it is possible to get dogi balls and brown boxes for free.
Dogi balls are obtainable from CC, which is really easy with an average team, just do F21-25 and you have 10% chance to get a dogiball, and you can also PLAY instead of PAY.
Brown boxes are available through Boss event, however the 10kk zeni is a bit.. too much, but it will definitely be lowered. Atleast I hope.