Every generation of Pokemon has it's own particular "style", for lack of a better word. For example, Each generation's Pokemon designs have the same general framework. The regions themselves each have their own unique atmosphere, etc.
But with each new generation, we see more and more that each generation is becoming less distinguishable from the last. These "styles" that the newer generations have are uninspired and are becoming more or less the same thing. Just look at Pachirisu and Emolga. But as the series is over 17 years old, this is no surprise. Despite this, we know that Gamefreak will continue the franchise as long as it makes money. And this won't change anytime soon at all.
So this is my question: When will the quality of the franchise decay? How long until Pokemon becomes monotonous and uninventive? Every cash cow series ends up like this, it is inevitable. But will you abandon ship by then, or support Pokemon until the bitter end?