Riot is considering removing flash from LoL. But the condition for it to happen is almost impossible
Is Riot thinking about adding new summoner spells? Yes.
Riot August has answered questions about summoner spells on his stream. This is an interesting issue because everything that is chosen very often gets nerfed right away.
Meanwhile, flash is chosen in 90% of games. In theory, then, this spell should be changed – according to Riot’s overall sense, this skill is chosen way too often. However, the developers do not change practically anything related to Flash. Why?
Flash can be replaced, but chances for it to happen are low
People on stream were curious why something with a 90% pickrate would not be changed. The questions were asked out of curiosity, not a desire to change. Rioter responded very simply by admitting that the developers are constantly thinking about adding new summoner spells and possibly replacing Flash.
The Rioter further explained that Flash makes LoL much better, and therefore gets special treatment compared to all the other spells.
At the same time, it is possible that one day Riot will come up with an idea of something that could replace Flash, but as we read, it would have to be something that would make LoL even better than Flash does, and it will be incredibly difficult.
This is why Riot allows Flash to be present in every game and worth picking on every character, etc. It is doubtful that anything better will ever come out, but of course, it is not out of the question.