I would assume that Chip has had him in a car a few times before signing him. And I read that he is only gonna do road/street courses. At his age it would be foolish to go to a more dangerous series and run the ovals at the speeds they run. Even he said that is not gonna happen. My guess is he probably wanted to run open wheel since he was young. If he doesn't do it now he will regret it for his remaining days. Nascar 20 years ago was paying way more than IRL/CART. Not sure about now though. I am not an open wheel fan. The cars are too fragile. But I will probably tune into a few races to see how he is doing.
The more the merrier, especially distinguished drivers from other racing disciplines.
A couple years of limited schedules from Johnson, or 500 one-offs from Alonso add to the show.
But, they're only subplots to the main show, which has an accomplished 40-year old series veteran like Dixon, mixing it up with a 43-year old Sato, and under-30 vets like Newgarden, as well as hard-charging youngsters like Herta, O'Ward, and Ferrucci playing roles.
The old guys will retire sooner rather than later, and others will take their place. Dixon is as good as they come, and presents his case, but the changing of the guard is in full effect, and to me, the more interesting aspect of the series, for now, and the future.