I've never liked fast travelling in this game, because it takes too long (game time; sprinting is faster). When I got access to the Institute's teleporter, I found that I could fast travel almost instantaneously, as long as I go via the Institute's HQ (A → Institute → B-). This has been very helpful when I'm about to fail a quest because I postponed it for too long, so I don't want to lose the teleport ability. If I decide to finish the main storyline, will I have to side with the Institute to keep it? (Not playing on PC, so mods and console commands can't help me.)