Maybe there's a small change of it coming back on occasion in the new upcoming weekly changing game mode?
Its not like the remnant on the summoner spells page is an indication of that, that's probably just Riots signature laziness or forgetfulness.
I mean it still has fans, and it only being available sometimes might reduce the bot problem and maybe increase people's interest for it a little due to its limited availability. Plus it would be a real shame to just throw out a whole maps worth of content while its still perfectly functional in theory. Right?
This is just my own guess, I have no sources whatsoever, I don't want to give you any false hope.