If Brexit goes well, I can see other countries being emboldened to leave

You are ignoring the geopolitical implications of Brexit and also you're making the same mistake in your assessment that the mainland Europeans made when they failed to grant Britain more concessions in the negotiation. The UK and mainland Europe countries see the EU very differently. For the UK the EU is synonymous with the USSR , for the mainland Europe countries ,including France and Germany, even though they don't really 'love' the EU, it is still seen as a cornerstone of their national economic policy and and major pillar of their security architecture.

It is seen as something complementary to NATO's hard power. The soft/economic power which is one more weapon that acts as a deterrent against aggressive economic moves and grants smaller countries the leverage and the clout that they could not dream of having on their own. For countries in the periphery, the prospect of joining the core European countries and partaking in their prosperity leads to more benign policies. For a recent example, the prospect of EU trade and eventual membership contributed as much as NATO bombing to leading Serbia to the negotiating table.

This is something that you as a Briton cannot comprehend because you have grown up in the safety of a first world economy far away from any potential European flash-points, such as the Baltics or the Balcans, so the risks to you are mostly benign.

But if you are Estonia, being part of NATO and the EU, makes you part of 'untouchable Europe'. You look eastwards at Ukraine and you are reminded what 'touchable' Europe looks like. So for Estonia facing an increasingly aggressive Russia, the potential disintegration of the EU is an extremely bad outcome. It opens the door to the Russian economic domination. If you are Greece, looking at an increasingly aggressive Turkey, an unstable middle east and facing an economic crisis, a weaker EU makes your world just a little bit more unstable. Before you say 'but we still have NATO' .We sure do, for now, but 20-30 years down the line I think the US will be rather busy in the Pacific and maybe not so committed to European security financially.

So whether other countries will leave ? No I don't think so. I think the outcome of the Brexit will be for European mainland countries to coalesce even closer around Germany, and not for any great love of the Germans, but simply because Britain has left them with no choice. I'm not British, so I have no business telling Britons how to vote. If Britons feel they're better off outside of the EU, good for them. They're a big economy I'm sure they'll do just fine.

What I find very troublesome though is this triumphalism about the 'impending demise' of the EU. For Britons the EU is just a trade agreement, for Europeans,even though they don't love it, they see it as contributing to their prosperity, their stability and their security. Trying to dismantle it, for example when Farage & Co team up with other euro-skeptics is seen as a bit of a dick move. I think these people should be careful what they wish for because a post-EU Europe with a collapsed Euro (leading to high unemployment Germany/France) might not be such a benign outcome.