I think that Prya might be the writers' way of getting Leonard and Penny back together. Prya doesn't want Penny hanging around so much and that will become a problem. Also, even though Penny never shared Leonard's love for all things geeky, she liked Leonard just the way he was. I have a feeling that Prya might try to change Leonard, have him be more ambitious and mainstream and that will eventually drive them apart as he realises he wants to be with someone who likes him for who he is now.
Then again, maybe I'm analysing this waaaaay too much.