don't you think that you should also extend exploration three-dimensionally if our age increases? in other words won't we have new planets and stars and asteroids to go around ; just not plain dull cities on the earth.
personally i think we will always have curiosity. the argument that things become dull is akin to the famous statements that everything that has to be invented has been [by some patent office officiando in the late 1800's]
human curiosity is infinite. if we don't get something tangible/physical to look we have enough brains to evolve virtual complex worlds [think math formulae, matrix etc] in our tiny little minds