People are looking at this as if it was one cycle of government ie a 5 year term. There will be uncertainty guaranteed in that time frame but the pound will go up and down as always, prices similarly.
If the vote is out, that is for at least the remainder of this century IMO. Over that longer time, there will probably be little overall effect on the UK prosperity either way. The markets would get used to changed circumstances, people will still buy and sell and make money or lose money.
So the main change will largely be political. How the UK is governed and how it sees itself in the world.
There is too much 'chicken little' hysteria around at the moment.
Uncertainty doesn't last forever - but the effect of the chance short term is unlikely to be good. Not sure about the long term myself.