Lots of effects...
1. There is a rush to safe assets by a lot of wealthy people, and most commodities are not safe assets. Precious metals and a few others may be, but otherwise this is bearish. To my mind this is the major short-term effect, and it will happen immediately.
2. The USD will rise, also bearish. This is actually part of 1.
3. Most economists are taking down DM growth by a few notches. Bearish, but not too much.
4. These very big market moves tend to feed on themselves. Who knows which hedge fund or shadow bank is overexposed and will default? How big will this be? By its very nature, it's hard to know. But the market will keep this in mind, and you can be sure that there will be sharp reactions to every rumor.
5. The biggest wild card is the effects on EM, particularly China. The first order effects (export slowdown) aren't too bad. But the effects of 1 and 4 may well cause problems. We will see.
The other side is how the world's central banks react to this. The obvious course is for rates to be lower for longer, maybe much lower for much longer. To my mind the key is whether we approach negative rates in the US. I do not believe the US population will stand for negative rates, and because of this monetary policy will lose effectiveness. Could be fun.
Longer term, a big question is what happens to the EU. To my mind it is obvious that they have to open up the regulatory system to political control and to reduce German control. Otherwise more countries will follow the UK's example. But people in power want to stay in power, so who knows?
The upside scenario is that the EU gets reformed, and Britain gets a good exit. The latter is not too unrealistic. Not talked about much is that Britain has a large trade deficit with Europe. And the items they import (German cars and French wine) are politically powerful. So there will be a lot of pressure to keep the UK in the trade loop.