A website design "trend" that looks like it's here to stay is flat design.
A flat design is one in which everything appears to by lying flat on a single surface. A simple name for a simple idea.
This design trend dates back to the 40s and 50s "Swiss Style" when grid-like, bold print ads were en vogue. The Swiss Style also gave us modern fonts like Helvetica.
The evolution of the internet has pushed beyond realism and three dimensional elements like dropshadows, and brought us to a design aesthetic that favors agility over realism. As users became more savvy, they no longer needed particular visual cues to help them know what to do.