If they decide to collaborate with big poker network such as ggpoker, they have bigger chance to survive with the poker.
Lets say Stake prefer to create their own poker network, I think it is not a bad idea since they have big player base already now and it is a good start.
Most other sites that failed in the past are mostly new sites that come with poker game only and started like from ZERO so it is reasonable if most of them failed.
Betcoin and fortunejak or may betnomi, these 3 sites did try to have poker but all of them also failed although they have player base but I'm sure the number of active players are not as big as what we can see in Stake.
I remember FortuneJack's poker, it was amazing but sadly no one was playing. I think that crypto casinos fail with Poker because almost all of them started with game Dice and crypto casino for me, an early user, is associated with dice. Since 2017, crypto casinos slowly adopted other games, add slots, sportsbooks, live casinos. I remember there was no Sportsbook on FortuneJack, Bitsler, Stake. We only had betcasino and nitrogen at first, then sportsbet.io was made in 2016. I think crypto casinos need to promote poker and they'll succeed.
Collaboration with poker networks is a quick solution. That won't be bad but I think casino, as big and popular as Stake is, can have its own network and is able to maintain it.