I agree there will be some locals, but it is a school day so those with kids may wait for Saturday. The big time Disney fanatics will be at the private party on the 4th, and lots of the locals may be waiting for Sunday with the filming in the park (Regis and Kathy Lee), I think that will be the worst day next week and not the 5th. Either way I find the parks very managable even with large crowds and it is pretty rare to reach "capacity".
By the way there is no set number of guests, it is a feel that causes them to close the gates. They do it in stages. First they stop selling walk up tickets and redirect to DCA. Ticket holders, AP holders still can go in. Only if that fails to control things will they really close the gates to all but resort guests. I think Thanksgiving day and Christmas day are about the only times this happens.
When CDA opened they expected 22,000 to line, they had 2000.
Additionally I think locals will be more excited about the real annivarsery date which is July 17th. Now that will be a busy day.