That is a terrible analogy. That is ending the tradition between the Yankees and the Red Sox.
You are still married, correct? Your marriage is still special to you, correct? All of the history and sentiment and commitment that you share with your wife is still present, correct? Marriage still includes straight couples, correct? It still includes all of the love and commitment and everything else that goes along with being married for them, correct?
All those things are still there and gay people are getting married at this very moment.
The tradition isn't being thrown away. We are just including more people in the tradition.