"how will they find someone so soon?".....Please...it's UCLA....which is in Los Angeles...you don't think there's even one important person they can find in one week? Of course there is....a director? an actor? a business mogul? A unemployed TV writer will be able to bang out a speech in 24 hours...that leaves plenty of time for rehearsing. You wait and see...they'll probably get someone amazing.
Considering their first choice was James Franco, no I don't think there's someone they can find that will be amazing.
Edit: Just saw they picked Brad Delson....I don't have any idea if he will be good or not since I've never even heard him talk haha. I've only heard chester and shinoda talk from linkin park but he seems to be a sort of obscure choice. Kind of weird that they couldn't get anyone much higher profile.