League of Legends MMO is definitely in development but that still doesn't mean the game will see the light of day and this straight from the lead's mouth.
Riot Games generates massive hype with pretty much anything the company releases these days and one of the reasons is that they don't settle for mediocrity. Possibly for the better, this is a double-edged sword that means sometimes games get chopped before they can be released if they don't satisfy certain standards.
It is for this reason that Greg Street, the lead on LoL MMO, recently mentioned that the current project he's working on may not even release at all . This may come as a shocker for most gamers who followed the development of the MMO but it does make sense when you factor in Riot's standards.
The company has released several games since the massive announcement during the 10th anniversary of League of Legends and all of them proved to be successful. On the other hand, we didn't see an unsuccessful title from them because these projects got axed before release.
Street's recent tweet probably draws from this perspective as Riot Games will likely decide not to release the MMO at all if they don't get the feeling the game has the potential to captivate the audience. On the other hand, if all goes to plan, there is no need to be afraid since the team is optimistic about the development so far.
The tweet might be a bit of a scare at this time but given the huge investments that go into MMOs and Street's confidence in the team, there are still no indicators things are going wrong.