From the Daily Mail:
Britons could need visas to visit France if the UK does crash out of the EU without a deal.
As Theresa May arrived in Brussels for a crunch summit, the French government ramped up its preparations for a no-deal Brexit and said Britons would become ‘nationals of third parties’ and would probably need travel permits to visit.
That's their unilateral decision, isn't it? You can't blame that on Brexit.