To me an interesting "Pro" approach would be not trying to replace a workstation or laptop but to complement it. For example, you set up a project in Final Cut Pro X on your mac and it automatically syncs an offline version to the iPad, on which you can work on the go and/or in new and different ways. This could possible with all kinds of different apps. Since the iPad has no file system or external storage possibilities, this complementary sync strategy would be great. You manage on your big system but work (additionally) on the iPad.
Another great option would be to use the iPad as an extended control surface with your big system. Use it as an input control with flexible buttons and sliders, or as a Wacom replacement with the pencil input. There are really so many possibilities, I just hope they get them together.
But I'm totally against iOS and OS X becoming the same thing, even though that is a very possible future. Imagine no file system, no terminal, no "going under the hood". Yes, many (perhaps most) users wouldn't mind and feel comfortable but it would sure contribute to the dumbing down of computer culture. Apple might not need the pro users (in terms of direct revenue), who would probably jump ship to linux lands, but they should realise that these users are much more important to the brand than what the mere numbers reveal. They are an integral part of what makes apple cutting edge.
“The iPad is the clearest expression of our vision of the future of personal computing.” – Tim Cook
I hope this vision leaves an open space for the real pros who love mac for the amazing operating system that it is.