Lets say that, in any given year, an average piano-professor may take in excess of 50 students. That is 50 individuals who want to be pianists, per year.
Allowing for changeover of pupils, that means each professor may teach more than 1000 pupils in his/her career, sometimes many more. So the ratio of professors to those who want to be professors is around 1000:1, at best.
Now for the bad news. On balance, around 50% of piano professors have gotten their job by "who they know", or other unbalanced arrangements. That means, unless your Aunt Mavis wills a million dollars to your preferred institution "for the betterment of the piano department", your odds of teaching there have just gone down to 2000:1.
Next, this "job", when Aunt Mavis helps you get it, is only really going to come when you're at least 30 or 35, so for the first 15 or so years, you're going to be working at 7/11, or possibly accompaning crappy first-year students, who have no idea how to play their concertos. And it will be hard to stay off drugs during this time. If you don't manage to stay away from them, your odds go directly to zero. It is OK to get addicted to alcohol and drugs AFTER you receive your contract as professor, but not before. In fact, it is "de rigeur".
And if you live in Australia, you can forget it totally, cos only foreigners get jobs here.
For those of you who dont live in Australia, your odds therefore just went back up to around 1980:1.
Good luck everyone:)