This is already happening. The market is getting saturated by those who think gambling is lucrative business. It's more like what happened in ICOs were lots of people who knew nothing about cryptocurrency nor believed in it launched their own coins and got the market saturated with lots of confusing and substandard projects
Those who have solid foundation will stay but those who are only after for the quick cash will always disappear. You can evaluate a gambling site if they have the intentions to operate long-term or short-term. One way to check is the gambling licenses they possess. If they find time to apply and acquire those licenses, I believe they are not here for couple of months or so but looking for years of operations. A developer can easily make a gambling website but to sustain it is another thing to consider. You can check also the amount of bankroll they have. A lot of them are faking their figures but you will know in time if they are faking the numbers on their site.