It'll eventually end, everything does. But I don't see anything on the horizon that will make it happen anytime soon. We're months away from the fifth gen release in japan, with us getting it in probably February or March of next year, along with possibly the third edition (ie like Platinum) two years after. Plus if/when we get remakes of Ruby/Sapphire.
We can expect new card sets to go with it, and if it's like most of them it'll be every new Pokemon at least once plus at least one new version of the previous 493, possibly including alternate forms, very possibly stuff from the new generation of bad guys and even gym stuff.
That's four to five years of Pokemon stuff right there, ignoring the fact that the anime and manga (I think) will also follow suit. As long as people like us keep buying and playing (the first really being the big thing there) Pokemon will be around with that horizon waiting for a long time. Of course when that time comes I'll be very sad because as it stands Pokemon is a big portion of my life.