Hey Camille, you seem very invested in this site but I always fear that my vocal teacher will stop teaching, become too busy or become famous and stop teaching altogether! Is that something I should worry about or is it not that bad to change your vocal teacher? I've just found it very hard to find an affordable great teacher in the past!

It can be a benefit to have more than one teacher! No single teacher is fantastic at everything. Over your lifetime, you take what you can from each teacher you have. 

Hopefully the good teachers publish articles, videos, podcasts, books, etc that allow you to continue learning from them even if they do stop teaching.