Ignoring the fact that Norris still has plenty of non-bat-related stuff to work on (and has yet to put significant time in at a league above single A), I think you're putting your definition of "real prospect" ridiculously high if you think Harper and Norris are the only ones we have. The Nats' farm system isn't loaded but it's not totally occupied by organizational guys, career minor leaguers, and failures.
We can start an old scrub that hit 2 homers last year, or go with the young buck who will be much better offensively. Pudge has declined defensively, so he's no longer elite. But, the Nats will keep starting old scrubs and losing 100 games. Norris has everything.