Europe is defenseless without NATO. All EU countries, with the exception of UK (yes), Greece (historically strong army because of Turkish threat) and Poland (rich experience with Russia) fail to meet NATO requirements on army spending. EU armies are disfunctional and barely able to provide symbolic support for the US Army in operations (remember Libya? EU couldn't sustain a few days of air-only operations).
It may very well be that NATO is done. But if it is, it's because of EU members that lack any will to defend themselves. So how do you expect EU's own defense to be any better than NATO backed by USA's might (politically ambiguous as it may be these days)? Again with the exception of Poland, whose EU-hated government is serious about defending the country, but that's too little, too late.