All the same the Schengen treaty is at risk with the current flood of immigrants. [1]
As far as the EU goes: I'm a Dutch citizen. And the NL have a long history of belonging to a coöperation of nations. Just after WWII it founed the BeNeLux. And it was a founding member of the EU later on. So I lived in a supra-national organisation for as long as I live. And I have to say that when I work here in the NL with people from France, Spain, Italy, Germany, ... I truly feel that we're all Europeans. It's some feeling of shared fate, shared history, shared culture, speaking their languages, intuïtively knowing their characteristic strengths and foibles. So as far as I'm concerned even if the current EU would fail we'll just start anew with an EU 2.0. Less expansionist and less idealistic probably. Sadder and wiser surely. But in my estimation the sense of a shared EU identity has become stronger than even the current vicissitudes or the meddling from billionaire investors.
[1] http://www.theguardian.com/world/2016/jan/21/dutch-pm-says-r...