[zachanker]

I actually had the same concerns, but after going through it they give you two ways to solve that:

One is you can set a backup phone to use to get into the account, it can even be the same phone you have the authenticator on, so as long as you have the same number, you can access it. The backup phone option can also work with landlines through voice.

They also allow you to print out a set of numbers you can use in case you lose the authenticator to get back into the account.

[edit] Added voice backup note.