<p>I’ll just pop in to say, once the OP hears back from Princeton (and good luck), he/she does not have to instantly withdraw from any/all the RD schools applied to. This is EA, so nonbinding. There is no reason not to wait and see what sort of merit aid may be in the offing, and even to compare FA offers (although Princeton is known to be tops in that regard, if one qualifies). </p>
<p>So, to reiterate–USC only has RD, is not in conflict with Princeton’s SCEA application policy, and the Dec deadline for scholarship consideration is not an EA or ED option.</p>