It is expensive to get there but these stellar bodies have resources which can be valuable. At some point it will become economically viable to do this.
If there is a huge breakthrough in fusion that will likely be enough to spark space colonization. Not only will that make moving through space significantly faster, it's also likely that new resources will be required to make fusion work, and while we may have enough on Earth to start it up there will be things we need from outer space.
Places that have water will almost definitely be part of this. And I wouldn't be surprised if the colonies were put under water (enclosed of course) since then they are far away from space radiation.
Yes, humans can live on this moon one day. I think that one day, humans will be able to live on any habitable area of any planet. It is just a matter of being able to travel to those places. Right now, it is not possible for us to travel to those places, but one day it will be.
No, I do not think that humans or animals will eventually be able to live on Saturn's moons, or on any other moons or planets. There are a lot of other factors that have to be right for habitation, not just an ocean. We have to consider things like air quality, gravity and temperature.
It would certainly take a lot more investigation than just the finding of a habitable ocean, but we are inching closer to finding a habitable place that could support human life. Whether that will ever amount to people living on Saturn's moon, it seems as though that's a question that will be answered in the distant future.
No, people could not live on this moon one day because "habitable" does not mean safe for humans. No one knows what the oxygen would be like on the moon. Plus, it is an ocean. Would a city be built on war? Maybe the ocean will be habitable for fish, but not us.