Stock photography has to catch up with lifestyle, technology, fashion, society, culture and architecture, among others. On top of that, stock sites sell news images as well.
So no, there always will be something to be photographed.
Sure, there will always be a market for hyperlocal and hyper-relevant stuff, but most of it is fairly timeless. Many of those landscape photos will be good 30 years from now.
Add in that an image competes globally and is infinitely scalable and that is essentially perfect competition with the prices to match.
There are trends for what looks good. If you look through some stock photos you can easily spot things uploaded years ago just from the style and quality alone. Just like all UIs are essentially the same thing, but you can tell which era the XP windows decorations came from.
But there is an upper limit to consumption. I know we keep pushing to see how much we can consume, but ultimately some FPS times the number of seconds in a day..
So no, there always will be something to be photographed.