Just because Google's doing it with Google Voice doesn't mean someone else's solution will automatically be "short lived".
Most of the world has still never heard of Google Voice (let alone "the cloud"). If he makes an SMS backup product, and sells it as that, I'm sure there will be plenty of people who would be interested, regardless of what Google is doing.
I didn't mean to imply that google was going to put him out of business, so much as I meant that I think carriers will likely follow Google's lead eventually -- They already have your SMS messages, call logs and voice mail data -- exposing them to the web effectively competes with a large portion of Google's Voice offering, and doesn't require significant overhaul of anything for carriers to implement. Of course, I could be wrong, but my point wasn't that he was sure to fail because he was competing with google as much as I feel things are trending that way already.
Besides, it's not like competing with Google is unwinnable either, it's just very, very hard to do.
Most of the world has still never heard of Google Voice (let alone "the cloud"). If he makes an SMS backup product, and sells it as that, I'm sure there will be plenty of people who would be interested, regardless of what Google is doing.