Correct me if I'm wrong here, but how old is Twisted Treeline? Season 3 or probably even older, and how much code was piled on top of that? Six seasons worth now, and you saw what happened when they replaced the death recap. A fucking death recap. Removing Twisted Treeline could possibly sunder all of Rune Terra and bring about mountains of unforeseeable code that could harm the game with more bugs than they already have. Keeping the damn game mode would keep people happy and not add more problems to the pile. Call me a doomsayer, but if they still go through with it and it happens, it will be fun to see the company burn.
**^ Main Point Above ^**
Edit: I'm glad that no one is toxic at least so far in refuting my points, but I saw some specifically that caught my eye and I would like to address. No other points will be addressed in the future.
"The code is self-contained in it's own module" - Yes, this would make removing TT very easy and something that doesn't affect the rest of the game. But then again people have been saying it was implemented in pre-season one, was Riot really thinking at that time their permanent game mode would be removed in the future? It's possible, but Riot hasn't released information about their code and I'm a skeptic.
"When they removed Dominion, nothing happened. Why would TT be any different?" - Well, my only argument would be the backpack from World of Warcraft. Hear me out, the base backpack you start with in the game is so embedded in the code that they couldn't do anything about removing/replacing it. It was one of the first things put into the game, so instead they added more bag slots if you authenticated your account. There are many reasons why TT would/wouldn't be different, that's why I just put it as a concern and not as something definite that will happen.