Depends on how much you want to know. We can make reasonable predictions about what would happen - but only within general tendencies. I think it's probably fair to predict, for example, that the UK would struggle to find deals with the rest of the world in a no-deal scenario because most other developed economies are members of trading blocs with similar rules for outsiders as the EU has. This is something that is the case now, and will probably be the case when we leave.
Beyond broad statements like that, though, it's extremely difficult to predict because (like it or not) so many factors about our situation post-Brexit do rely on what we can get from the negotiations - and they obviously aren't completed yet.
So at the moment if you want to talk Brexit speculation is all you have, and speculation is indeed pointless. But then again so is just about everything that gets written on the Answerbank, and so are most things that one does in one's everyday life. So if it's enjoyable or stimulating, speculate away.