The only thing I’ve noticed about art changing over time, in Graphic Design, is that it gets more and more beautiful, and more and more professional looking (skill seems to be passed down from generation to generation).
If you look at the kind of architecture we had back in the 70’s, things are much more beautifully designed now, what with a lot of modern homes having these wood finishes and smooth, dark tones to complement them.
Clothing doesn’t look so lazy. Everyone looks like their clothes fit them and make them look good.
Color choice is a major aspect of art changing over time, what with brighter, more vibrant colors being used today (used smartly).
Look at cars from the 90’s and cars of today. It’s like artists actually started trying to give them shape, instead of having us drive around in grey, rectangle shaped boxes with wheels.
What will art look like 50–100 years from now? Way better than it does now. Look at futuristic concept art. It’s built in us to want to achieve these types designs, and at some point, our society may look exactly how we envision it.