If I create Google Account without Gmail today, will I be able to change my mind and acquire Gmail address in the future, keeping the same Google Account? (The last part is important because other people might share content with a Google account I give them so I don't really want to be changing Google accounts altogether.)
Yes, you will be able to do so.
If you add Gmail to your Google Account, your account's primary username will permanently change to email@example.com.
After you add Gmail, the original email address associated with your account will become your alternate email address. If you have verified your original email address before adding Gmail, you will be able to sign in using this email address.
Adding Gmail to an existing Google Account
- Go to mail.google.com.
- Click Sign up for Gmail.
- At the top of the page, click If you already have a Google Account, you can sign in here. You'll be redirected to a sign-in page.
- Use your existing Google Account username and password to sign in. On the next page, you'll see a shortened Gmail sign-up form where you can choose your Gmail username