It certainly would be nice to have SVP included within madVR. It would remove AviSynth dependency and avoid having to run SvpManager in the background.
This also would give more control as to the order of operations.
There are more and more 120hz TVs which is GREAT with SVP, while madVR is coming out with even better (hungry) algorithms. Videos upscaled with NNEDI3 and SuperRes look GREAT!
However... it's practically impossible to pull out all the juice even with the top cards.
At 120hz, you get 8mz to render each frame. To upscale 1080p video into 4k with NNEDI3 and SuperRes, I don't think you'll achieve that in 8ms even with a Titan X.
If, however, madVR would run first, a 24fps video would have 41ms to render each frame with madVR, then SVP could easily generate extra frames from there. When you think about it this way, the performance cost on the GpU would 5x lower in this scenario by processing madVR before SVP, which isn't currently possible, but which would be possible if both were somehow integrated.
That's very unlikely to happen in the near future though.