While I understand why some people like new worlds I find more interesting enhancements/extensions of the old courses on Watopia world. First of all the village of Watopia is more Tirolean than anything on Tirol course. Also riding Watopia give you more sense of freedom to explore than any other world.
I think it would be great if you could create an alternative route from the jungle to the relay top of the mountain (or some similar route) and from top Alpe du Zwift top on the other side towards Vucano part of the island, an alternative Stelvio route. These two routes would give people alternatives not to return on the same route (which could be boring even riding a bike in real life).
You could also extend Watopia east of Vulcano with a savanna flattish to rolling hills gravel route featuring giraffes, elephants and other savanna specific animals.