You place your bets at Pinnacle, but do you already play poker in other casinos, or other poker sites as well? Unless you're truly a poker player, what difference would Stake bring for the users of BitcoinTalk if they develop and build their own poker service? Why would you say that you'll leave them if they don't offer poker?
Good question and I have an even better answer.
First off, yes I played poker for a long time, right when the hype started in 2003. Been through many sites and places.
For real poker players it would be heaven if stake added poker, maybe only in the beginning though.
Imagine all these players at stake, losing at sports and in the casino. Maybe they just know the basics of poker and now want to "try their luck" at the poker tables. That's what real players are dreaming of. It would be easy to win their money. Obviously over time the word spreads and more and more good players would come to stake to pick up those fishy players but until then it's go time.
You could compare it with Macao when they first introduced poker there. Rich Chinese business men basically burned their cash losing against just a hand full of pros. Nowadays they pros are travelling to and even living in Macao just to pick up these easy $.
By the way, where are you coming up with the story I would leave stake if they don't add poker? I am already leaving stake (because of the weak sportsbook), but I will come back when they add poker, for the just mentioned reasons.