I'd trade Vandoorne for Gasley in a heart beat.
the think you need to consider is who are you comparing with
Vandorne is compared to alonso
Gasly is compared to a hartley.
Vandorne if you look at his race simulation on friday practice, he is almost matching him. and if he doing that compared to alonso he is pretty good.
gasly on the other hand , his race simulation are much better to hartley. but hartely is struggling. he is quite old for f1 now and if you want to know, he was a reject of the redbull young driver program. he went to WEC , which is an endurance racing and did well to get back to f1. for f1 you need to be quick every lap, hartley is not, he is more suited to endurance racing. so it is obvious that gasly who is a gp2 champion will be much quicker than hartley. let say if gasly is quicker than norris in a TR, then i would say gasly is special talent.