Opinions about regarding Google as a utility aside, I think the comparison this argument makes isn't as comparable as you make it sound. Using your example with telephone companies, this situation is like saying a specific 3rd party service accessed via telephone should be regulated without actually regulating the telephone companies first. I would like to see ISPs be regulated as a utility before individual web sites are regulated as such.

In the event that becomes reality, the time would have to be taken to define what minimum level of services the web site would have to offer. Simply saying Google must keep X service available would be archaic. Would other email providers be exempt from having to maintain these rights? If your job gave you an email address, would they have to maintain it after you leave the company? These are probably contrived questions, but ones that would certainly have to be answered first.