In 2017 there are several imminent National Elections in EU countries. In particular the results of those in France and Germany could then even lead to changes of not only some fundamental EU principles, but also the way in which "current" problems are tackled !
In 1958 Treaty of Rome was adopted and signed by the six founding Countries. In 2009 the Treaty of Lisbon, which updated the functioning of the EU, was signed by all the 27 EU member countries.
Now in all EU countries, small but growing Nationalist Parties want more security, effective Frontier Controls, no immigrants, only temporary refugees, and less dumping of low cost Asian Goods !
There are also loud voices which want less political interference via "Brussels Directives" in local political Issues. In other words, National Parliaments want to recover the right to solve their local problems ! This implies the EU format must change.
The urgence for changes in the EU has been accelerated by the Acts of Terrorism and the War by Extreme Islamists in the Middle East. It is one of the major reasons why there are now other "Brexits" being considered.
But, in the EU, can anything change quickly, before September, by which time certain key EU National Elections will have been decided and properly digested ?