Not claiming to know everything (and even before it appears on the market) I kind of refrain from putting exact numbers on this case.
Nevertheless I am convinced that it is quite correct to state that most current lenses and also the better older lenses can be used with what appears today to be very high MP bodies, such as the rumoured 46 MP body.
I expect serious problems to appear only in case of compromise designs, for example cheap super-zoom lenses, which are likely to be used out-of-context of what they had been designed for. You will also be more likely to see defects/errors in other designs doing pixel-peeping, but related to the end product (a picture) what would be the point? Walls/prints/screens won't magically become larger, only crops in photos will contain more detail. That doesn't necessarily force us to crop from a corner of a lens with noticeable corner distortion and there are correction possibilities in post-processing, too, so I don't see old lenses going bad all of a sudden. We will just be more susceptible to buying better lenses, because we will be able to see the difference with increased clarity.