There will never be 57 countries.
According to Austrian newspaper "Wiener Zeitung" it is rumored that Australia takes part in Vienna
Down Under beim Song Contest? - Wiener Zeitung Online
Why? China and Japan are different cases than Australia.If Australia can take part, then China and Japan can also be eligible to do it. It would soon be a Worldvision.
So Eurovision.TV posted an article stating that at the moment, there are 38 countries confirmed with Albania and Greece hopefully confirming soon. These numbers don't add up. Only 37 countries have (this can be seen on the wikipedia article if Albania and Greece are excluded). This can mean two things. Either Eurovision.TV messed up on their numbers or one country has confirmed that we don't know about. Which?