I play League a fair bit and though I don't much care for the...lore such as it is, this seems like an exceptionally bad handling of...whatever it is they're trying to do. You know how when a dev decides to make a big change to their long running game or series they often post a blog or video that clearly illustrates their intent and how they're going to make it happen within a few nicely summed up paragraphs? This is not one of those.
Their recent posts about how the lore is going to 'evolve' really do not explain much at all, pretty much just saying they are going to move things forward and make them better without definitively explaining or outlining how they are going to do so, and not really acknowledging that they're essentially doing a massive retcon in what looks to be an attempt to keep the old fans happy. They also haven't explained what the direct substitute for the League itself will be and how summoner spells and the like will now work. On top of that they aren't even solid about what they thought was wrong in the first place, 'The institutions we'd designed fostered creative stagnation, limiting the ways that champions, factions and Runeterra itself could grow and change', ok, what exactly does that mean for what you want to do and how will your upcoming alternative avoid this and be better? All this kind of lack of real information does is piss even more people off and invite a shitload of speculation.
When it comes down to it it seems like they're still trying to keep to the real status-quo at the core of LoL, that of badass characters smashing the crap out of each other in an arena over and over again, whilst pushing the narrative beyond that in a meaningful way. But why even make a real attempt at that when you must conform to the original confines anyway? How will you instill changes and give a feeling of progression beyond new champs, visual updates and changes to the meta in a game fundamentally about doing the same thing over and over? It's extremely unlikely that say, a character will ever be killed off or noticeably change in a way that can be reflected in game as not only would it piss a hell of a lot of fans off that they've tampered with their precious ''name of champion here'', but it wouldn't be feasible to record a bunch more lines and touch up the appearance of a champ every time something happens to them in the setting. In short, fleshing out and developing 100+ characters and having those changes represented in any kind of meaningful way in game is just not going to happen.
I honestly don't see why they couldn't have just kept everything as it is, throw out a special event with a mode or map like Howling Abyss every now and then, gradually retcon some of the crappier lore, work towards less crappy lore with new champs and the like and start up something like a weekly comic series focusing on a different champ or group of champs each time. That'd give the lore junkies something to keep 'em happy without interfering with the game itself, can cover all sorts of characters and events and can be made relatively quickly and easily with little risk, rather than announcing some kind of big grand plan to apparently totally revamp the setting for the better.
Maybe there's some part of this big project I'm not just not getting, but hell, with how vague Riot are being with all this and the general suckiness of the lore they've already established (for every interesting idea there's 10 Mary Sues, extreme inconsistencies, nonsensical designs or boring cliches) I wouldn't count on them to do any part of it very well, and if they're going to try to commit to this it sounds like they've assigned themselves a mammoth task.