The rumored complete comedy revamp at NBC is happening. After a slew of cancellations yesterday, (Whitney, Guys With Kids, 1600 Penn, Up All Night), the network just pulled the plug on freshman Go On. So far, only one NBC comedy series, Parks And Recreation, has been renewed. Only two others are still alive — freshman The New Normal and veteran Community, whose fate is being determined in a complex multi-show negotiation between NBC and Sony but is looking good. Go On, which marked Friends star Matthew Perry’s return to NBC, started off strong, buoyed by a Voice lead-in. But it gradually started to slip, lost its rating footing once The Voice went to hiatus and never regained it. Rumors that NBC may discard almost all of its existing comedy series began surfacing early this month when word started to get out that the network is very happy with its comedy pilots.