I prefer the current format, there is no need to expand the postseason. That would reduce the competitive nature of the game by allowing bad teams go against very good teams and the fun is taken out of it. There wouldn't be as many meaningful games in wildcard games or first round games. There would be many blowouts and lopsided games. Stay with the current format, do not change anything about the postseason.
Having said that, it would be nice to have new teams or relocate some, to cities where football would mean a lot and to bring some benefit to those cities, but that has nothing to do with the postseason, they can very well add teams to divisions and all of them they would still have to fight to win the division and/or a wildcard spot. Los Angeles would be a good city for a team, however they need a stadium first.