As I've said in a different link I think that Italian unification was reaching a boiling point regardless of what Napoleon did. His intervention strangely made it both easier, by siding with Sardinia against Austria, and harder, by protecting the Pope, taking Nice and Savoy and signing a premature treaty with Austria. Either way though Cavour and Garibaldi were still working to unite the Italian states.
Germany too was moving unceasingly towards unification. It is likely that without Napoleon, France could have avoided a humiliating war. But having been top dog on the Continent for so long, conceding this spot to a united Germany would have been a bitter pill to swallow. Even without Napoleon it is likely there would have been a war between Prussia/the German states and France. Without Napoleon's ego it is more likely that France could have found some allies, perhaps Austria or Russia, before jumping into the conflict unprepared.
Benjamin