One advantage you have as the arranger keyboard player in a band is that you are the only indispensable member. If someone else doesn't show up, u can just unmute the track, lol.
Seriously though, I've heard some pro touring bands, Dave Matthews comes to mind, have the whole set on WAV files and if someone is sick or has a problem they just stick someone in there and he sync/plays to the WAV file.
Just don't try it on Saturday Night Live!