All your lenses will produce better resolution on a higher MP sensor.
Lenses don't "out resolve" sensors, and sensors don't "out resolve" lenses. The system resolution will always be lower than the lower performing part of that system. The 50 f1.8 will resolve a lot more on the new cameras too, just not as much as a 200 f2.
Even a theoretical 'perfect' lens wouldn't resolve 50MP from the new cameras, it just doesn't work like that.
http://www.canonrumors.com/forum/index.php?topic=25215.msg498253#msg498253
We have to get over this idiotic 'this lens isn't good enough for that sensor", "that lens out resolves this sensor" garbage, it just displays a complete lack of understanding of a pretty simple idea.
Nothing is perfect, no lens, even a theoretical perfect lens, will resolve every pixel on a sensor even if it doesn't have an AA filter.
No sensor can resolve 100% of any lenses resolution capability.
The end resolution will be lower than the lowest potential of any of the single elements in the system.
Any EF lens will resolve more on a higher MP sensor than a lower one.
How much resolution you need for any single image is entirely moot and only you can decide.