The Twisted Treeline should become a lot more important map.
Since few years, Riot focuses on reducing the average length of games. A lot of people don't like that and wish to go back to longer games. Meanwhile, we have the Twisted Treeline, a barely touched and played map that have the length that Riot tries to attain in the Summoner Rift.
Riot should put the Twisted Treeline more in the spotlights and start to balance the game around it a lot more than it does now (ideally with a new balance team dedicated to it), so it becomes the 20-35 minutes length they wish for, while giving back to Summoner Rift its old 35-45 length.
With the upcoming preseason, the game is going to change A LOT. Maybe now is the time to give attention to the Twisted Treeline as well.