i believe the provisions file and the certification file will not work anymore, and you need those files to build your app.
what i have understood is, every debug b4i check provisions and certification files and if your account is closed then those files should not work anymore.
i get this emails too. Also that my certificate will expire.
I´ll try to create new one for development and one for AdHoc, they will expire in one year. So i can try to develop on my own device till them ..
i have already 13 apps in ios and also got a low revenue (15$ sales in the last year) but still i renewed my account.
i think it is important to be able to create for all available platforms.