The most important fork is whether Greece will stay in the Euro zone (we're not talking about EU, but about the zone of the shared currency, the euro) or will leave it and go back to drachmas.

Keep in mind that leaving euro and introducing drachmas is not a single action, but a process that takes at least a few months. Arguably, Greece has already started on this way.

I am pretty sure we will see Greek government IOUs (scrip) in circulation soon.

The Tsipras government doesn't look to be either willing or able to come to an agreement with the Troika. The interesting question is whether it will be kicked out of power before the conversion to drachmas becomes irreversible (in the medium term). Keep in mind that there are valid economic reasons for Greece to prefer having its own currency.