To understand where the iPad Pro fits into the world, you have to understand that the shift from laptops to tablets is more of a generational shift.... The product is not quite there yet and will take another product generation or three to refine, and the key user groups for the product are still quite young, but Apple has no choice. It has hypotheses about use cases that need to be tested and refined in the real world and it can only do that by shipping out real products.
I cannot predict the future, but I doubt this is it, at least for me, my students, or anyone I've worked with over the last few years. As others have said, it lacks OSX, and that alone will make it unusable for too many situations. Anyone who has tried to make a complex Excel sheet, Word document, or PowerPoint presentation ought to know what I'm talking about. In many cases it *can* be done, but no one *wants* to be hobbled by the interface and iOS limitations.
Don't get me wrong. Ive got an iPad and I am thrilled with it. I've pushed it pretty far with content creation (much of my dissertation writing and research occurred on it). I may get an iPad Pro someday to replace my iPad, but the rmb is an incredible machine that I wouldn't want to work without, and the iPad (regular or Pro) isn't a substitute for it (or the rmbp). The Surface Pro is very, very tempting. I think the next iteration just might be the one that pushes it into the mainstream -- it seems to me like it is the next generation in computing. It's the OS (and the lack of my favorite apps), though, that keeps me from getting it (and maybe that keeps others from getting it as well). An OSX (optimized for touch) Surface Pro would be cool, but it won't happen anytime soon, if at all.
We've got to work with what we have now, not with what we might get in the future. I'd recommend that anyone thinking about replacing their OSX or Windows device with this iOS one turn off their computers, put them in a drawer somewhere, and go a week with the iPad. If you can do that, maybe it's OK for your workflow.