From what I know there's only one field of online gambling were it is still possible to create something which will be in demand among gamblers. It is poker. With the recent closing of poker section by established gambling sites a niche has been created and I constantly see like poker fans play on crappy sites just because they love the game. I'm talking about poker tournaments and table games where people can play against each other, not about video poker which is more like a slot game to me.
There are actually gambling sites that do offer poker but later on they do remove it due to lack of demand.I agree there are really gamblers who do seek out these card game but not totally even on those dice or slots.
Seen those poker sites but actually they vanished either non profitable for them or no interest just like what you said.
If gambling sites aren't making any good money then we wont see a very big industry on gambling.