Oh really? The Islamist sure look like they are winning to me.
You're right. It's a three-front war. The first front is the terror attacks, like this one. The terrorists get wiped out. Does that mean they have lost?
No! Because the second front is the propaganda war. These attacks make the islamists look bold, and unstoppable. Advantage to the islamists.
And the third front is the immigration war. Advantage to the islamists, again.
So what will stop them? Perhaps this (odd) combination: Trump + Putin + Marine Le Pen.
They will continue to do this as long as it works for them.