If you go back and look at the history of productivity apps you’ll see that each major user interface shift led to new classes of productivity apps. Back in the 70s and 80s, when computers had text-based interfaces, word processor applications like Wordperfect and spreadsheet applications like Lotus 1-2-3 were invented. In the 80s and 90s, when graphical interfaces became popular, presentation apps like Powerpoint and photo editing apps like Photoshop were invented. If the historical pattern repeats, productivity apps that are “native” to the tablet will be invented.
Things like Paper strike me as getting there already.
Word processing works on tablets now, but presentations and spreadsheets don’t. Presentations, with apps like Haiku, are easier to translate. The biggest opportunity is figuring out how to translate spreadsheets into a tablet native environment