Chivalry, and Etiquette are different things in my mind, if related.
Chivalry is the value sets expected of one who seeks to be "Knightly", or chivalrous.
Etiquette is behaving socially gracefully in whatever context you happen to be.
Yes, they are related, since acting properly in public is a lot easier if your value set espouses being a decent human being.
But chivalry in many ways will and has, stayed the same. The core tenets, stripped of the social context (the realm of etiquette) still exist. Etiquette changes rapidly and drastically. The etiquette of the 19th century is as inappropriate today as the etiquette of the 15th century in the 19th century.
Etiquette varies region to region. The details (and in some cases, major parts) of etiquette can change just as fast as the cultural groups you interact with. Good luck using American socialization on Germans, and have fun getting a beat down in Saudi Arabia by propping your feet up on a desk and revealing the bottom of your shoes.
Stay modern, chivalrous, cultured and classy gentlemen.