I think it is too late for Europe to to crack down on terror, given the way terror has evolved. The first step of cracking down the terror was to prevents immigrants from war tone Syria. All terror cases reported have been conducted by immigrants some who are in the country illegally.
There have been several times that terrorists have attacked in Europe. There was the attack with the truck on Bastille Day. There was the attack on the night club concert in Paris. Now there is the attack in Berlin. The terrorists have already arrived. The governments of Europe do not tell them to leave and then it is too late.
It is not too late for Europe to crack down on terror. The real problem is that terror is not always something that can be cracked down on. There is so much that can be done such as background scans and proper identifications which can be improved upon as well as communication ways between countries. However, to truly improve terrorism the people have to improve their attitudes towards each other.
The killers have already spread through Europe like cancer, so the authorities have no choice but to combat them. They have to catch up to the rest of the world through cooperation and viligence. It is never too late because many of the perpetrators are on watch lists, Europe just needs to enforce the laws.