If there is actually no oil price recovery for 7 years

Venezuela, Russia and possibly Iran would be bankrupt as countries.Maybe others too. However, the more each country is dependent on oil revenues the closer to bankruptcy each country would be.

What effect would this have on the U.S. and Europe?

It's hard to say at this point. There might not be that much difference for Europe or the U.S. However, oil people around the world (unless they have diversified their investments) would be bankrupt a lot too.

The reason why it would have a neutral effect generally speaking in Europe and the U.S. is because lower oil prices would allow both sets of economies to be generally more successful because you would be paying much less for oil to make plastics. This in turn makes things like Cell phones, parts of cars and other devices much less expensive. So, more people will have cell phones, laptops, cars and be able to afford to drive those cars, it will make food less expensive than it would have been, airline tickets will be lower and everything you have shipped to you will cost less because gas and diesel is less.

However, the oil industry in the U.S. as far as searching for, drilling and mining for oil (includes shale oil) will be a completely disaster over 7 years if this is true.

However, for the ecologists it is much less likely that fragile regions in Alaska will be drilled for oil (for at least another 7 years) until prices spike. However, most U.S. and international oil companies might be somewhat out of business or just drillers and shale oil miners by then.