No, the Constitution is not the least bit dated. There is a mechanism in place to change and update it when necessary.
It has served us very well for 200+ years. Most of the Western Hemisphere has been governed by a series of dictatorships during that time period, but thanks to the Constitution, the U.S. has flourished both economically and politically.
Nothing devised by men is ever going to be perfect, but the U.S. Constitution is about as close as you are going to get.