The last option is the only answer. Devs are going to just have to suck it up and make VR games that can run at 4K and 90fps. And players are just going to have to suck it up and tone down whatever settings they need to for it to run optimally as well. The sacrifice will be worth it though. Does that damage the future potential of VR ports? Probably. But it's necessary, and ports aren't going to be the real bread and butter of VR anyway. They need at least 90fps/1440p for CV1 and I'm willing to bet CV2 at the very latest will be 4K.
Amazing life-like Crysis like graphics aren't necessary to blow people's minds in VR. I've shown to my friends both Project Cars and Live For Speed and the outright "blowing of minds" aspect between the two is no different.