Ah, I missed that. It's hard to say with certainty whether horseback riding diminished the popularity of foot races since it happened such a long time ago and at a time where probably neither was considered a sport or entertainment.

I do think that technological advances in general affect the appeal of certain games and sports by rendering them less mysterious or by bringing them further from a real world activity/situation.

Of course, I'm talking about relative, not absolute, popularity. Chess and horseback riding will remain popular for a long, long time.