All in all it's up to each individual country to consider their membership of the EU, there's a lot that can be said for both parties and opinions. Though Britain has been the "odd one out" within the EU countries on a number of topics, and I can only imagine these kind of discussions to start gaining traction in other countries if the UK is allowed to redefine their membership agreements under the threat of leaving.
Aside from that, it'd be likely the UK would be sustaining some negative hits on the topic of global trade agreements and import/export as well as the possibility of having to deal with a couple thousand more refugees crossing the canal if France doesn't play nice and expels the border guards currently deployed on the mainland, as that's a pretty hot topic over there right now.