I don't know how many practice runs and how many laps to a practice NASCAR gets, but once you get a feel of the car and the track i doubt its not nearly as daunting as it looks.
I don't imagine that the speeds or the track would upset him one bit, but there is never a situation in F1 that could ever prepare anyone going into and thru a corner at 190+ mph with 2 other cars right next to you. Wait till he gets bump drafted for the first time or what will he think when the car behind him fills his rear view mirror and there is another car off his right or left door just 3 feet away and he is only 10 ft behind the car in front of him ... for the whole straight away and then into the corner. You never see those situations in an F1 race.
As Larry the Cable Guy would say ... that's some scary watermelon right there ... I don't care who you are.
I have a feeling that if he does join NASCAR, he will be a lot humbler than his fans are with regards to him racing on a NASCAR track. He may have been god's gift to F1, but that doesn't mean that he will saunter into NASCAR and dominate like he did in F1. If JPM is any indication of a F1 driver transitioning to NASCAR, it will be quite awhile before he see the podium.
I would wish him all the best and hope he has a fruitful career in NASCAR, but all this F1 drivers are the cream of the crop crap and NASCAR drivers can only turn left ... please.
Jeff Gordon and Jimmie Johnson showed the world that NASCAR drivers can turn left and right.
EDIT : When was the last time you went 200+ mph and 190+ mph thru a corner ? I have done 135 on the back stretch of Watkins Glen and then down to 80+ into the "bus stop" ... I don't know about you, but it made my hole pucker each and every time.