It's a unique time to be an Astros fan. Very few teams have jumped leagues in the modern baseball era, with the last being the Milwaukee Brewers. There will most likely never again be important games in the regular season with the Cardinals or Cubs, playoff disappointment handed to us by the Braves (unless it's a World Series), or reliving the 1986 NLCS against the Mets. It will now be almost as unimportant as any other Interleague Series. Although I disliked these teams, I also respected them, followed them, and watched their games even if they weren't playing the Astros.
Now that the Astros are in the AL West those rivalries are gone, and we have to look forward to future games against the Mariners, Athletics, Rangers, and Angels. After one season against these teams, we have never had a meaningful game against any of these teams. I know people will point to the Rangers and think that since it's Dallas that we have to have a rivalry, but to me it feels more like an arranged marriage. Yep, we exist in the same geographic location, but are they a real rival? They have never prevented us from reaching the playoffs, and we have never done the same to them
I'm thinking that Oakland will be our future rivals since they have built a team that has sustainable success, but maybe the Rangers will one day naturally become our rivals. Who knows? Maybe in 2017 the Twins will prevent us from facing the Cubs in the World Series. Sounds weird right?