This is a favourite POD of mine, and it's one that crops up an awful lot. I'm surprised nobody's done a TL on it.
Otto was attempting to rule like a Byzantine Emperor in a world that had drastically moved on from Late Antiquity, but for all that, he did have some successes. If he lives twenty or thirty years, I think a revolt or two back in Germany is likely, due to Otto's apparent intent to rule from Rome: how the Emperor deals with these will be important to his future. If he's sensible, he'll probably try to start constructing a proper imperial bureaucracy and hierarchy, perhaps at the urging of his wife Theophano.