Google+ Accounts – Migrate to Google Apps for Domain

Are you asking if the account will be deleted? If so, the answer is no according to Google.

Google will not delete inactive email accounts on your domain. Instead, as an administrator, you can create and delete email accounts on your domain when necessary.

EDIT: Once the account is setup, it doesn't seem like it but I'm not certain. There's no mention of inactivity other than verifying the setup here: http://www.google.com/support/a/bin/answer.py?answer=33419

Your account has been deactivated or deleted. For example, Google deactivates your account if you do not complete the steps required to verify ownership of the domain within 14 days (7 days for Standard Edition). It is also possible for an administrator at your domain to manually delete the account. In either case, you will need to go to http://www.google.com/a to reregister your domain. You will have to wait five days from the time the account was deleted before reregistering. Any data in the deleted account will be lost.

If it's a Google product which doesn't take Google Apps for your Domain accounts, then you're currently out-of-luck. You're waiting on Google to support that.

You can create a gmail account and forward the mail to your normal address. Make sure the secondary email address (the password-reset one) is pointed to a place you actually read and trust. The set up forwarding, inside Gmail. Then you can continue reading email in the one place and have an account to use for those products that specifically require a Gmail-account.