I think the days of any start-up (new) gaming site raising thousands of BTC in bankroll funds is effectively over. It really is all about the reputation of the owners but even so since each BTC is worth a huge amount investors will find great difficult in parting with their funds.
I still think that people would be willing to put in "some" money into it, even if not a ton. I understand that new startups will not be able to get as much invested as bustabit, but just drop your rate to like 1% instead of 15% and you get yourself a big advantage.
Aside from that there are now places that try to make money on their own token instead of just the casino and that is the real money these days. You create a website, you give people token for gambling, that token gives people dividends from gamblers, then you own 30+ percent of that token total and you make dividends while simply selling your tokens to highest bidder in the end. Long story short there are more ways to make money for new startups these days, even if not getting the bankroll funded, it is still something else that could be done and that is how they end up surviving.