Let's enter in the spirit of looking at the positive sides. I suspect some posters will now try to rip my head off and tell me I'm wrong and a rabid brexiteer!
However, I'm coming at this thinking that a hard Brexit is looking more and more likely so what are the potential upsides that my children could benefit from (and therefore we can plan / help them with). Note - I am in London so there is a bit of a London-bias to some of these.
Some positives:
Maybe we avoid going to a world where there are a few large blocs US, EU, Russia, China going head to head on trade, influence. A more global view / betterment of humanity would be nice!
I think we are going into a new global recession. By leaving the EU it reduces the risk of the UK needing to bail out Italy, Portugal, Spain, Ireland etc.
Outside of the EU trading rules the UK can re-value the pound and adjust trade deals as required (useful in a global recession).
Recession may mean lower house prices. However if banks leave London for EU cities then that also should lower house prices in London as demand lowers.
The UK could strengthen ties with the Commonwealth - economically and socially. Historic ties which have not been helped by EU membership (but not been massively impeded either!).
The UK will probably need to re-balance the economy a bit more, better food production, less importing, more local manufacture and recycling. I think there has to be environmental benefits there avoiding food miles.
Schools will lose students if families leave the UK. So more teacher contact time (but school funding hit by fewer students on-roll).
Increased opportunities in highly skilled jobs in the UK where people have left due to Brexit (Medical professions / scientists / engineers / teaching).
Maybe, just maybe, we might see a change in politics. From recognising the diversity of voters wishes to the frustrating state of both main parties.
Each of these positives can be viewed negatively too. But looking for opportunities and positives in a period of uncertainty is my approach.