There are many possible alternatives to c/c/p in “idea space”, and the little details matter. A better system, though, would have some of these properties: it would persistently store cut/copied content in some kind of list, at least content of manageable size; it would have some way to see the clipboard visually/spatially; it would interact with drag/drop; it would give some visual indication that there was currently copied content, and perhaps the type as well; it would allow a user to interact with the history of cut/copied items in a more flexible way both from keyboard and mouse; it would allow easy conversion of copied chunks into “documents”/“files”/“pages” in their own right.

Many of the problems here intersect with the problems of our current files + hierarchical filesystem + semi-spatial file browser + open/save dialog system for dealing with “content” in general. Ideally, a generally more intuitive and flexible basis for these problems would be built, and the replacement for c/c/p would integrate with these other tools. That’s sort of wishful thinking though. (Well, the idea of replacing c/c/p is also probably wishful thinking. Systemically different approaches like the Canon Cat word processor are all pretty much dead by now.)

Many of your requirements are met by Ditto (on Windows) and ClipMenu (on the Mac). The basic model is: Ctrl-V pastes like usual, Ctrl-Shift-V pops up a menu of every previous paste. Previous items can be selected and pasted using either the keyboard or the mouse. This gives you persistence, visual display of the clipboard, and keyboard and mouse interaction with the history. And it turns out to be insanely useful. Oh man. I would never go back.