If they solidly tie this into Unity, it'll be very good for so many things. Even if they have to middleware the hell out of it for XBone/PS4, it'll be good. Hopefully the console makers do just run with it, so they'll never run out of 3rd party publishers/titles/developers to work with.
Between x86 architecture for all major gaming platforms, Vulkan running GPU calls for everything (including mobile and linux-style small ends), it'll make things easier to do.
They may not necessarily be optimized, but they can actually be credibly done, without a huge clusterfuck in theory. Best thing I've heard in ages for developers.
For gamers as well. It's not my fault if PS4/XBone can't run my stuff properly. It could if they properly implemented Vulkan and made proper drivers for it. Everything else can. Why can't their "uber console"?
I know it's currently looked at as the other way around. But only right now. Vulkan sort of wants you to write your own driver and shaders etc, but give it a few months. There'll be good, quick, generic tie-ins on all fronts, for all major development environments, for every end-user coder/developer, for every major gaming platform. Plus the ability to just "do your own thing" if you really want to (or can) for a platform, if you need to play with hardware directly as a developer.
It's like directX, but for everything (not microsoft/windows exclusive). And within a few months, you'll always wonder what those specific Nvidia/AMD driver updates were ever for (they were for games that you weren't even playing, that didn't play nice with the hardware you have). And better/prettier games and framerates will come from it.