New trees and buildings for old islands

[JJonth Cheeky Monkey 1]

I wonder if there is a way to make the old islands, like everon to have the new trees and stuff, the old trees suck compared and the new ones seem to run quicker on my machine , but not as an addon, i mean change the actual islands, so if you did the Cold war crisis campaing the islands you were fighting on have this new stuff, or maybe BIS is working on this now