I view this as an antiquated approach to having access to your documents between your "desktop" and "tablet". As much as I hate the word, the future of sharing and accessing documents between devices is in the "cloud". Music and video are already headed in that direction. Services like Dropbox and Evernote have made huge strides. Web apps are also taking us there. And Google's Chromebook intends for everything to be in the cloud.
For sure, right now, it's not a purely seamless task if I say, create a Powerpoint presentation on my Mac and want to share it with someone on my iPad later at a lunch meeting. But, it's not rocket science either. I just throw it into my Dropbox folder. Then I open it from my Dropbox folder on my iPad. But I see these types of tasks becoming automated in the future until it becomes the norm. I don't think local storage will ever go away completely, but I do think it will be used for niche or archaic reasons.