it's a travel forum, not a soapbox.
Oooh - may we quote you on that in future?

"Sure, no-one knows what exactly will happen, that doesn't mean that with a bit of common sense you can make a reasonable estimate of what will happen."
OK ninjabambi, tell me what your common sense tells you will probably happen if the banks continue to stay closed.
The ECB gave the Greek banks E89 billion to keep them open but most if not all of that is now gone. That is the reason for the Greek banks closing this week and imposing ATM limits. If there is a NO vote on Sunday, the probability is that the banks will remain closed, no more funds will be forthcoming from the ECB and the banks will end up literally with empty drawers including ATMs. There wil be no cash to withdraw. That is a very real probability and could happen next week.
The economy of Greece will be forced into a nearly all cash (or IOUs) state. Here is a quote with the link supplied.
"The result would be a series of intriguing but catastrophic complications. The economy wouldn’t stop, exactly, but finding ways to conduct everyday transactions would suddenly become all-consuming. For as long as banks stayed closed, Greeks would have to find ways to get by without using the financial system and accessing their own savings—using cash they had withdrawn before the closures or IOUs, for example."
http://www.theatlantic.com/business/archive/2015/06/grexit-default-preparation-drachma/396386/
So what does your common sense tell you will happen when the people cannot get any cash ninjabambi? Just what do you think 'all-consuming' used in the above quote might look like?

Common sense tells me that a complete closure of banks for an extended amount of time is extremely unlikely. It would imply that people have no money at all and would have the choice between going hungry and criminality. This would equal to sinking the refugee boats at sea with the refugees in it. That would not be allowed any time soon.
As you already quote, the economy would not stop, it gets complicated. There would probably be supply chain interruptions due to payment/trust issue's. Where there is a profitable market there are people that find ways to serve that market.

From The Guardian newspaper, July 1
"The signs of mega economic gridlock were evident all over Athens--- and not only in the form of shops, empty restaurants, and queues outside cash dispensers. Ferry boats sailing from the city's port of Pireaus were bereft of passengers. Public transport was noticeably thinner, the result of fuel reserves running low while supermarkets were showing signs of panic buying, with food staples at an all-time low.
At what is almost the height of the tourist season, hotels are also feeling the heat, with a reported 40 percent drop in airline and tour operator bookings.
Athens' failure to meet yesterday's debt repayment to the IMF has resulted in mass cancellations by US travel companies.
"American tour operators were ready to make transactions," said Ionnis Retzos, President of the Panhellenic Federation of Hotels, "but they couldn't when US authorities warned them that money transactions to Greek banks would be impounded."
For what it worths or not (up to each individual) you may want to check this thread from an other forum with daily reports of people's experience on the ground kenko
http://tinyurl.com/nsuv6kn
We're getting real-time reports here in Australia from travellers / professionals in Athens and they are saying it's pretty chaotic street-wise and bank-wise etc.
Not sure about hotels, tours, ferries, etc, further from Athens.
If you mean chaotic street-wise in terms of road traffic I believe you. If you mean chaotic as in public unrest, it is now my turn to question your motives Ian??? Unless your friends have never been to Greece before and describe Athens chaotic due to the Syndagma Square demostatrions??? Chaotic as on unrest it is not!

. As explained to me by an economist- it's an ominous sign when the banking problems expand from ATM's to international corporate fund transfers becoming impossible for technical/legal reasons. The banking system has become frozen, which freezes the economy.
Cash and carry will become the modus operandi.
If you mean chaotic street-wise in terms of road traffic I believe you. If you mean chaotic as in public unrest, it is now my turn to question your motives Ian???
No - I have no particular motives or agenda - I am in the thread for three reasons: (1) I was recently in Greece and loved the experience, (2) I have relatives visiting next week, and (3) I have an abiding interest in international affairs. Is that enough?
The media reports we are getting (and okay - I agree they could be beefed up for the purposes of drama) advise that there are large street demonstrations, and that banking is very bad. I haven't even addressed the more serious point from kenko that international transactions may be compromised ... if so that's pretty serious for tourists, no?
As I say - no dog in this fight - just an interested bystander.
There are large demostrations around Syndagma square every evening, half of them to promote a No and half of them to promote a Yes on the coming referendum. KKE, the Greek Communist Party and PAME, its syndicalist institution, usually make demostrations starting from Omonoia Square and parading towards Propylaia or occasionaly Syndagma area but the next large demostration they announced is on July 11th around Greek Ministry of Culture (Nikis street a couple of streets below Syndagma Square)... Demostrations are a thing happening in Greece at least since the late '70s/early '80s, I can not understand what the fusse created by media during recent years is about...
If international transactions get compromised is an other matter and this might be quite serious both for locals and visitors ...but we have to wait and see.