As noted in another thread, it is even worse when you are on the other side.
We heard about reports from last year, when the border was closed due to the fights in Khorog, but travellers could sneak through by bribing. This was not possible this time. So you have to rely on your embassy to get you out. Not all embassies are theat responsive, so perhaps best is to be American and better to not be covered by the Brits (a motorbiker ended up in going all the way to Kabul, after waiting over 8 days).
Having said that, if going to the Wakhan you should very well consider the risk of not beeing let through back to Tajikistan. In the aftermath we learnt, that the Tajiks are closing more often than thought the frontier for some time (2-4 weeks). They use then epidemies as reason, in this case it was true as near Faizabad were some people ill of cholera, but at other occasions, this was just a simple excuse for closing the frontier, without any substance.