Dont forget there were two play offs places in Southern League (Tiverton & Merthyr both lost) , and another 2 (at least... im not sure) in Isthmian and Northern.
As for next placed teams in league. There are 3 who would claim that.
My guess is Conference North will run for 1 season with 21 clubs (wonder if I can get a rebate on my season ticket?).