There's about 0.0001% chance Italy will leave the EU any time soon. I don't really understand why this referendum is being likened to Brexit, Trump and whatnot, this is mostly a matter of internal politics. Sure, this will likely bring about a government crisis, but those are as frequent as Trump saying 'terrific' in Italy.
Personally, as an Italian living abroad, I didn't vote cause they had my old UK address in their recordings, so yea. Would have voted yes, mostly cause the alternatives to Renzi are looking horrible. But hey, it's nice not to have lost for once, growing up in Berlusconi's Italy was though. Sure I could have chosen a better country to emigrate to than the UK from that point of view, the likes of May, Cameron and Farage really made re-evaluate the whole Italian political class. I'd take Silvio and his antics over those evil morons any day of the week.