For a company that builds game engines? Yes, in four years you will likely need to be pursuing some type of VR support structure unless VR crashes and burns (which is also entirely possible).
But for a normal development company? Nah. Even if VR takes off, which it likely won't to the extremely optimistic degree a lot of people are assuming, there will always be an enormous market for non-VR games. Especially since none of the current three consoles were built to natively support VR - they don't have enough power, they're just now working on the peripheral, and they have no software support almost two years into the lifecycle. Which means, best case scenario is that the next generation of consoles, or whatever system the future holds if not consoles, is where mainstream VR for gaming might actually take off. But that's at least 4-5-6 years away before that generation even begins. And then you'd be looking at another 2-3 years of software development and hardware sales to build a library worth the price of admission.
And even then, there are way too many people who either aren't interested in, don't like, or can't physically use VR for the industry to abandon traditional gaming altogether. And, in all likelihood due to the cost and nature of the product compared to the alternative, it is far more likely that VR becomes a niche while traditional remains the mainstream rather than mainstream becoming the niche with VR taking the forefront.
