I'm not exactly sure what the problem is, but consider that Google is already backing up your contacts. It has them in the cloud.
I'm guessing you're worried that if you delete a contact, say Roy Hodgson, from your phone, that it will automatically disappear from the clould. And when you later decide you want Roy's number back, you won't have it.
And have ever entered Time Machine with Contacts the current application? You can go back in time, search for a contact and selectively restored that contact from the chosen time in the past.
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