Why you are assuming that they won't last long in youtube? Are you expecting that youtube is going to do the same as twitch did? No I don't think so because I've seen different contents in youtube and some can even be called inappropriate but they haven't been removed up until now.
Other than youtube, there are other streaming sites out there which are not strict as twitch. They can always use that. They can also create their own streaming platform as you suggested. It will never be a problem for them since they have a lot of money. They can hire a good website developer and then run some promotions. Pretty sure that many top gambling sites or those who got removed from twitch are going to migrate there.
I am something new and I have learned a lot in the casinos, Drake is a very influential character, I think that wherever he goes, he can destroy because he moves masses, he is also very cool and that is what people like, if they say to a network similar to Twitch I'm sure everyone would fly there. Stake is the biggest casino in the forum ? they have a lot of publicity and their site is quite easy to manage, and they sponsor many athletes and soccer teams, that means that their success is great, in duelbits they are also doing things well, and little by little they are having more cvisitors, more players who want to keep coming in and winning.