The best thing about the conclusion was whoever you are, you are right!
Vi is right, Cait is right, Jinx is right, same with the rest (Jayce, Mel, Vik etc) and the best part was Silco who also was right (by not going for the exchange). Can you believe it? Even Silco (a villian) made sense. It's not caricaturistic bad man like most movies/shows provides since forever. He had reasons, he's loyal, he's radical.
If someone comes up with ''ending sucked'', then s/he's poisoned by stupid cliche Holywood/superheroe movies.
No sir, this is not your average ending with ''kiss'' or happy conclusion.
This ending built where they want you to imagine how Piltover and Zaun and all those characters are now. This is their condition. This is where they are and how they are.
About next season:
The reason why most tv shows/movies fail is ''stretching'' the current story or literally putting filler episodes.
For example Stranger Things: It should've end in season 1. But they forced it for 3 more seasons and each season it's getting worse. Why? Because those characters and that story in that town is saturated.
But Arcane's story is developing so fast that i'm sure there are still even more stories/scenes there they skipped.
The only thing i'm curious is....how the hell are they gonna keep the quality on this level, again? Sounds impossible...
*Edited for typo.