Twisted Treeline needs some loving from Riot. There have been innumerable threads opened up on this fact in both GD and the 3v3 forum. Sadly, Riot has not spared a single red post or a single mention in Champion Spotlights or any other promotional video for more than a few months, now.
The more attention that we, as a community, bring to this sad issue, the sooner Riot might feel obligated to at least share some insight into their future plans for what I, and many others, consider to be a great part of this great game.
There are lots of ways that Riot could update the map, that's for sure. Check out the Twisted Treeline forum for plenty of topics discussing different ideas.
More importantly, though, the (large) part of the community that plays Twisted Treeline is looking for at least a notice, a word or two, *something* from Riot that indicates they have plans for the map aside from letting it and its community fade away.