I am afraid to say, that those suggestions are what we everybody know already about. Ain't gonna happen now or soon, but not impossible either.
Free Roaming with random point-to-point racing in open world is quite fun. Or even Car Navigation! Technically it isn't racing, but sport anyway. Actually, with layout, you can also make platform puzzling, going for with not-so-racing-skills required, but more like accuracy.
Again, it is not related for racing... but we have cruising tho.
Just let's stop suggest these due we all know about these, with reasons and things. It is already proven to be a fact that devs do their things on their own way, and we shall respect of it, or go away and make your own product.
Sure, you can always suggest some! Just go for something new