Is Opting out of "cloud" use possible?

I like to keep all my files local, and never want to upload anything to the "cloud". Is there going to be a way in the new Macs and the new OS to make sure that everything is kept local and there is not one bit (bit as in part of a byte) of my data going online if I don't want it to.

If Apple doesn't include a way to do this then I will have to have two computers, one for my stuff and one that's connected to the internet. Right now I only keep my programs and OS on the computer, and all my data is stored on a removable HD which is disconnected when online. It's not that I have any really sensitive data, but I want to remain in control of what I do have, "convenience of iCloud" be ******.