I was thinking about using some brighter colors in my kitchen but I'm worried that, while they may look fun and cool now, they'll get dated right away. Is this true? Do more vibrant color schemes date themselves sooner?

Not necessarily, but when they do, it's so much more obvious. I had the same concern--we took the safe way out by using the bright colors for wall (and ceiling) paint, cabinet knobs, linens, accessories, etc.

You might also try a "now" variation of a classic color. We went with a brand-new red release--Lady Bug, I think--from Sherwin Wiliams, and used it only on the soffit near the ceiling and an accent wall in the adjoining dining room. We paired it with a neutral but noticable tan/sand and I think it worked well.

It is often better to stick with a neutral colour scheme and introduce bold (spot) colours as accessories or wall hangings.