depends if the BF4 beta is really a "Beta" or a Demo like BF3s "beta" was.
true beta's come 6 months or more Before release date and they last a long time.
this gives developers time to really get feedback and fix stuff.
a beta that comes within 1 month of release date is really a demo - nothing major will get changed before release.
In fact, looking at disaster releases like Diablo 3, MOH warfighter, SimCITY, etc.
You could say most modern game titles are released BEFORE they are even finished and get day 1 patches - IF you are even so lucky to get fixes on day 1.