You nailed it, I think. If surveillance works, then Paris, Beirut, Bagdad et al wouldn't have happed. Realizing it's a pipe dream, I'd love to see a world accept that we the west have done so much damage that nothing will stop terrorism.

Accepting that means we can throw those wasted resources at things that have a better chance of working - throw the tech that detects copyright infringements at detecting pro-ISIL sites, and use DCMA-style tactics to take them down. Fund new research to put effective bomb and weapon detectors into every doorway. Because protecting borders doesn't work either (crunchy on the outside, soft on the inside). Build schools, instead of bombing them. Stop selling weapons to the very people that shouldn't have them. Teach politicians to value non-American lives as much as American ones. Stop honouring violent death, and honour the deaths of people who move humanity forward instead.

There's an endless stream of ideas of what we could do, if only we actually wanted it.