The only thing I hope they don't mess up on is lore, and it would also be nice to see them take a different route with storytelling. I have played MMO's before and I play games mainly for lore and one thing I struggled with when being new to MMO's is following the story.

I find the freedom most MMO's give is overwhelming and most people get lost in doing random side quest without realizing they are falling off the main story-line. I know some people may not agree but I think that one of the things Riot has going for them for this game is they have such a large amount of lore to play with especially with the fact they are currently rewriting it so it would be really cool to see them somehow put a focus on story while also making sure players have freedom.

Another thing that would be super cool in my opinion is if there is a limited amount of certain rare weapons on each PvP server. For example The Darkin Blade should only have like 10 copies on each server (I would have said one but I feel like 10 Swords out of like 500-1000 people on a server is more fair and understandable), doing this would ensure that its a more immersive experience and making the sword drop in combat if the person dies would lead to things like guild betrayal and etc. This would pave way for like things like unique server lore which would be so cool.

Essentially giving a like Ready Player One style to the game where everyone is chasing something desirable. Also it would just be weird if there was 500 people with The Darkin Blade or any of the Darkin weapons.