Grexit? Brexit? Exit?

I am wondering if "Grexit" would be such a bad thing. It might save the Greeks.
I have always had doubts about the idea of a European Union. Possibly it started out as a good idea. You know the sort of thing I mean - freeing up trade and movement across borders. They aren't bad ideas at all but perhaps that is about as far as it should go.
The Euro was an interesting idea but it has always puzzled me. It made assumptions about individual currencies and their value. When the UK decided to retain the pound I decided that perhaps the Euro was not the answer to Europe's economic woes. 
Europe is not a level playing field. It never will be.
There are reports that people are withdrawing money from Greek banks at an alarming rate. They are apparently sending money into France. They must consider this option to be a good deal safer. I suspect I might do the same if I lived there. 
But what if the Greek government decided on "Grexit"? They would need to make an announcement and stop all financial activity immediately after the announcement was made. Presumably they would then have some sort of arrangements in place to allow local buying and selling of essential items until they could get a new currency minted and in place. Would they go back to the drachma? 
It probably wouldn't be worth much for a start but that might not be a bad thing because it would surely boost the tourist industry. Greece would be a "cheap" destination. If they could handle the influx then money would come in. Use it wisely and the country could be back on its financial feet in perhaps a decade or so. It would be an ambitious move.
I doubt the rest of Europe wants this. It suits Germany in particular to have Greece in debt. They want to be paid - but they want to be paid under their terms. Britain must be worried too. There is a fair amount of British money propping Greece up at present - and that is without them actually using the Euro. 
And, if Greece went Grexit then what would happen to Britain? Would they be more likely to go Brexit? That must worry Germany. It has done well out of the European Union, very well indeed. It has made Germany powerful and influential in a powerful and influential super state. But if the European Union disintegrated into individual states again then much of that power and influence would be lost.
There has, in the past, been talk of a common currency between Australia and New Zealand. It hasn't happened. Despite that they seem to get along with each other and the rest of the world. So, does a common currency really matter? 
In one sense it obviously doesn't. Business can still be done. People can still buy and sell and barter. Greece would be "poor" for a while but it might actually become better off.  The International Olympic Committee could do the right thing and invest in a permanent home for the Games in Greece. It would save the Greek economy - and many more besides.
The rest of the European Union might be unhappy though because, I suspect, it's really a power thing.