I think we need to expect at least one major terrorist attack each week worldwide during next 5 or 10 years

Why?

Because as ISIS is defeated on the battlefields of the Islamic State it doesn't have to defend real estate anymore. But, it is still the richest terrorist organization in the history of the earth. Though it's finances may slowly reduce over time without being land owners and hostage takers and organ sellers of the organs taken from those they beheaded, you have to understand they still have millions and millions of dollars. They will NOT have to pay their soldiers to fight. So, where is that money going to go?

It will go to kalashnikovs, and bomb vests distributed around the world to restaurants, airports and public places. I also think we have to expect bigger and bigger explosions during the next 5 to 10 years from ISIS because they don't have to defend any territory and they can turn their finances completely upon destroying the world economy instead in a strategic way for their cause. So, as their most dedicated soldiers not killed on the battlefield return home to wherever they live on earth expect some of them to strap on bomb vests take Xanax (so they are not afraid to die) and blow themselves up in crowded places all over the world.

This will horrify the world, reduce tourism where the bombs hit worldwide and change a lot how people see themselves and each other, harm the EU and reduce worldwide tourism. Will it collapse the world economy? That's hard to say right now. But not preparing for this eventuality is to be really stupid as a world economy and a world of many nations.

Big wars are not possible because of nuclear weapons because the Earth would turn into an asteroid belt with all life upon it gone forever. So, terrorism appears to be what we are left with to deal with here on earth for hundreds of years to come. In some ways this is worse than the World Wars of the 20th Century as we can see already in it's long term effects on the world economy and of free nation states worldwide.

Unfortunately, this will tend to reduce human rights worldwide and only cause more terrorism as people feel intimidated in new ways throughout this century. It will tend to cause more and more poverty as terrorist wars cause many regions of the world to become uninhabitable.

At present, I see no useful solution to all of this. However, as in the past, "Necessity is the mother of invention" is always necessary for the human race to survive here on earth and to go beyond this and prosper.