In my opinion, old casinos are disappearing because of the tight competition and old casinos tend not to develop their casinos and refuse to follow progress, that's why they lose competitiveness, the newest casinos always come with a different appearance with more and more features, but old casinos don't add them that's why they are almost extinct
In the case of Freebitcoin that si exactly what happened to them before they decided to keep the money of people hostage and not to comply with withdrawals. They refused to re-invest the money they got on renewing their user interface, getting more games and adding value to their gambling experience. Eventually, all that translated to loss of gamblers and volume of money going through their ecosystem.
Not all casinos suffer this destiny, though, there have been old school casinos which recognized the value of Bitcoin, Ethereum and other blockchains to become global casinos.
That being said, there is still much potential in brick-and-mortar casinos and bookies, as there will be always people seeking for the experience of being in a gambling floor, instead of gambling from their homes.