I don't think on-site solutions are necessarily more secure than the cloud. Obviously in some industries there's a regulatory component to where data can be stored & who can access it. But, an IT department staffed with a number of people who aren't keeping up with their skills may not be storing their data as securely as a cloud service would.

I picture cloud services becoming like a bank for data. Today, we'd laugh if someone said they stored their life savings under their mattress because it's more secure than a bank. I can see the day when storing all your data physically on site would be equivalent to keeping money under the mattress.