Depending on the type of Brexit deal with the EU, or other deals the UK may make with the EEA, it may have little direct impact on Expats in the EU or EEA. If Brexit includes the UK staying in the Single Market there will obviously be little direct effect on Expats, but the UK and Norway have supposedly already made some agreement on mutual citizens rights after Brexit, as have the UK and the EU which May is now trying to get through Parliament. I haven't seen much in the way of detail yet, it might not happen!
I want the UK to stay in the EU not only because I think we will all be better off financially, as all the evidence suggests, but also because I think European countries should stick together in making Europe more safe, peaceful, environmentally safer, and able to travel freely within, plus, plus... I want to see the UK contributing more, not pulling out like a spoilt kid when the others won't all play your game. Staying in will give both the EU countries and the UK, British input which for example the "Norway option" doesn't give Norway. History confirms staying close with your neighbours is better than not.