If you uninstall your Google Auth you’ll lose all your tokens. Some services offer backup codes and these codes are valid only for this services. For example, Google offers backup codes, so if you lose your token you can use these backup codes to restore an access only to your Google account. If you lose the token and don’t have a backup code you should contact the support team of service you protect with 2FA. They will help you to restore an access to your account.
Tip: in the process of token enrolment save the QR code and keep it in a SAFE place. Then if you lose your phone you’ll be able to restore your token on a new device.
Another solution is a hardware token that can be used as a backup. For example, Protectimus (the company I work for) offers reprogrammable tokens Protectimus Slim NFC. They can be used as backup tokens (1 token can store 1 seed and can be reprogrammed an unlimited number of times).