Only 1-10 at NCAAs were automatically qualified to start with. Those 6 teams you mentioned and the 4 Ivy teams weren't automatically in until the Ivies dropped out. If they wanted in, they would have had to take place in the ping pong ball lottery like last year, and hope to be one of 6 teams drawn who finished between 11-20 at NCAAs. Since 4 of the teams between 11-20 are declining, no ping pong lottery is necessary, except for Penn State's spot if they decline.
So, If Penn State and all the other top 16 teams accept, then the field is set (no lottery necessary). If Penn State declines, they will have to add one more team.