I think there are more people interested in crypto than we think and we just have to stay vigilant in spreading the word. Get people engaged and show them that crypto is here to stay. That along with new ways to use their crypto(such as poker) will be the way to get more and more interested in crypto.
Several crypto gambling sites tried attracting poker lovers, but failed primarily due to bad execution and losses. Stake will probably end up in a similar situation even if they actually decide to add poker later.
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.