I tire of the let's put down dot coms becuase all these new tlds are so great threads.
Most quality dot coms will increase in value. You have to look at each name differently, not bundle to whole world of com into one ball.
For example, if you sit on a dot com of bestloans, the value of this domain will just increase more each year imo, regardless of new gtlds.
But if you have dot coms that are, and lets be honest, low-medium and under in quality, then you may lose out to other gtlds.
Some people seem to think dot com is doomed... what world are they living in? Not this one.
Good day.