If you receive a new email address or can no longer access an old one, the update will be performed. Your Apple ID is important for protecting your account. To update your Apple ID:
Changing the e-mail address that you use as an Apple ID is not difficult under the right circumstances. If your Apple ID is a third-party e-mail address, such as: Gmail.com or outlook.com, you can choose a different third-party address when changing your Apple ID. However, if your Apple ID is an Apple email address, such as icloud.com, it is unlikely that you will be able to change your Apple ID. In the following, this scenario will be described in more detail.
Changing your Apple ID
First, go to appleid.apple.com and sign in.
Then, in the Account section, click Edit.
Click "Change Apple ID" under your Apple ID. 
Enter the e-mail address you want to use as the new Apple ID, and then click Next.
You may see a list of Apple email addresses associated with your Apple ID. If this is an icloud.com, me.com, or mac.com address. Select the address you want to use, then click Next. If not, read on.
Change your Apple ID as an Apple email address
If your Apple ID is an Apple email account Mail Address Is Ending Apple's documentation on cloud.com, me.com, or mac.com states that you can choose one of your aliases to become your new Apple ID. As mentioned earlier, you can not change an Apple ID that uses an Apple email address to an address provided by a third party, such as Gmail or Outlook. If you have not linked additional Apple email addresses with your account, you will not be able to change your Apple ID at all.
During our tests, however, it was impossible to change the Apple ID or its associated ID to an alias with it. When creating an email alias, it can not be used as an Apple ID. So all you have to do is create a brand new iCloud email address and set up a new Apple ID.
We contacted Apple to clarify this, but did not receive a satisfactory response. We will update this manual if it changes in the future. In the meantime, if you need to change an existing Apple ID associated with an Apple email address, we recommend that you contact Apple Support.