tie rods do not need to be replaced in pairs.

its A. plausible to get another 50,000 miles out the existing one on the opposite side, and B. its just about the easiest piece of the front suspension to change, so if you do need to replace it, wont be hard later to do it. I did one when I bought an 83 because a boot was ripped and it was loose, and never replaced the other one for the rest of the time I owned the car. It was still good when I sold it.

Id only replace the one in question, and inspect the boots of the other one like you have. If its good and still tight, there is no reason to change it at this time.

__________________
This post brought to you by Carl's Jr.