Yes! All the big tire companies, Goodyear, Michelin and Firestone have a "natural rubber" development department and every couple years they come out with a "green tire" which they quickly drop and forget about.
As for the "technology" of natural rubber, yes again, ALL military aircraft tires are only natural rubber, people know, when it matters use ONLY natural rubber.
Again, we use choose to use and pollute with synthetic rubber because it is more profitable for the companies to sell us more tires that ware out more quickly. They know this and its on purpose.