I've made reservations through Disney Travel and was told that there was no guaranteed re-entry for that day (July 17th). Ou package is for July 15-18. He didn't say anything about the other days, but they seemed to aniticpate larger crowds that day than the 15, 16, and 18.
I know it will be busy, but they 50th anniversary won't happen again.
I have booked other reservations after that for that week and hope everyone will go home after that weekend, so it won't be so crowded the rest of the week.....I can only hope.