Well, two men would be impacted, and the entire F1 history with them.
First is Teddy Mayer, who handled McLaren in the 70's with some success but it ended badly and he was sacked.
And the second one, of course, is Ron Dennis, who merged his own team with McLaren in 1981, and went to stratospheric success with Lauda, Prost, Senna, and later Hakkinen and into the 2000's.
Of course if Bruce McLaren had lived, Mayer would never have replaced him, and ron Dennis a decade later would be buterflied away. A shame, because a Bruce McLaren / Ron Dennis alliance is intriguing.
How about him testing in either CART or IRL, after the split, or perhaps before the split ? Dang, his death was really NASCAR very own Imola 94...
Imagine, if Earnhardt added Indianapolis, Le Mans, Monaco to his NASCAR stellar career... well, a bit like Jacky Ickx, except with the Daytona 500

Or Mario Andretti
https://en.wikipedia.org/wiki/Mario_Andretti
https://en.wikipedia.org/wiki/Jacky_Ickx
When one thinks about it, the top races in Motorsport are
- Monaco (or F1 championship)
- Indianapolis (or Indycar championship)
- Daytona 500
- Le Mans
- Monte Carlo (WRC)
- Paris Dakar (WRC, 2.0)
Only few pilots ever come close to win all of this. Fact is NASCAR is a world apart from the others.We need a NASCAR top pilot younfg enough to move across all the other ones after winning the Daytona 500.