On the other, that the EU is robust and united enough to start undertaking plans to create an EU army.
Which is it?
Both. The politicians in the main are pro EU and many (but not all) want to strengthen its powers further and move to full union. On the other hand the demos largely do not love the EU and some politicians are with the people on that.
As in all political matters the situation is complex and there are a range of views.
It is possible that a Brexit could give hope to anti EU supporters across Europe, but of course that is what the EU fears, and this is why they are caught between offering Britain a good deal (single market without free movement, or sectoral membership of the free market) which would of course benefit them too, and playing hardball in the hope that the British economy suffers and thus frightening would be Frexiters (and other Euroexiters) to 'hold to nurse for fear of finding somethign worse'. The latter would be an extremely risky game though.