There is a community forming right now that aims to write a MOBA from scratch, mostly fueled due to the Vanguard incident on Linux. I am not affiliated with the project, but wanted to raise attention to it (as I am currently on cold League turkey since a month).
At this point, LoL has become synonymous to MOBA.
A bit like Kleenex has become synonymous to tissues.
As long as they don’t tow the line with copyrighted LoL material, they should be good to go.