Thinking about it a bit, there is probably one area where lenses could use improvement: Image Stabilization.
Higher resolution sensors are great in that they capture more detail, and having optics that can resolve enough detail to make that additional detail valuable is also great. However the greater the pixel density, the more likely camera shake is going to affect the results...mitigating or eliminating any detail gains you might have otherwise had.
I think improved IS on telephoto lenses, pushing the envelope beyond the current 4-stop improvement to 5- or 6-stops, would probably be useful. I think it might also be valuable to see 2- to 3-stop IS on wide to normal zooms, like the 24-70, 24-105, maybe even the 16-35, etc. For those who need cropping power more than native resolution, and do things like wildlife, bird, airplane and other forms of photography that involve hand-held or gymbal-mounted operation, better IS might be essential to actually utilizing that additional sensor resolution.