Personally I would love the option to plug in an ssd-disk, solely for those games with massive loading times. That's the setup I have on my PC, and it works very well.
Why not plug in a solid state SSD-disk drive? That's the setup I have on my console, and it works very well.
It'll void your warranty, but I've heard of people replacing the internal disk in their PS4 with an SSD, and it does exactly what you'd expect when it comes to load times.
I'm amazed that Sony/MS don't offer it as an option at a fat markup, I guess they will wait until later in this generation.