Eh. I felt like Amon was too omnipresent to hang around. If they wanted him to be a longer term enemy, Korra would have had to be much more involved in regular Republic City stuff. Amon showed up earlier enough and pretty much completely took over the show outside of the little bit with Tarrlock. To keep him around he would have had to not show up until pretty far into Season One (after the equalists were established as a threat). Were I writing it, though, I would have had the Tournament go on much longer, and had the Triads and Gangs be the first round of major foes. The equalists would be implied to simply be another gang, until (dramatic twist) Amon shows up and reveals their true goal. And then end the season with the attack on the Stadium and the end of the Tournament. Edit: But then again, I would also have done the show as an hour long Drama targeted at older audiences, rather than a Saturday Morning Cartoon.