Just as seriously optimistic, as those who are seriously pessimistic about Brexit!
If, and I emphasis the if, there is a no deal Brexit then fundamental changes are likely to happen, to our economy yes and to society as well, and there will of course be winners and losers. Those who are currently losing out will want to be optimistic about the change coming, those who see themselves as winning will quite rightly feel pessimistic about any change, but change will come whatever.
Possibly being outside the EU will force the UK to get a better balance in its economy less dependant on Banking and other services, people as diverse as JRM and JC see this from an optimistic standpoint (different results of course) but throwing off the shackles of the EU is something they both look forward too!
I was being ironic, but the fact is the one thing we know for certain if there is a No deal, many more Customs officers, port authority personnel etc. will be required, so its definite job creation in that sense.
I've said on other posts I don't believe there will be a Brexit, of any kind, our current crop of politicians are too scared to take that leap and now the Labour party has broken ranks, one or two Tories will be looking side-wards at each other. Politicians do not have a death wish mentality and will sell their own grandmothers, never mind constituents to keep their jobs. A way will be found to avoid Brexit and to blame the people as well for that decision!