Biochan

I wouldn't call it pointless, it would be cool to see more character development, after what we got this season, with Nya learning to relax from Ronin, and Ronin to be more loyal from Nya. It would sorta tie up that story arc as a nice conclusion, with Nya growing up, her transition to be a ninja - something that she has felt left out of since 2011 - was important, but who would be Samurai X? What would happen to all the cool gear in the Samurai Cave? I think that the best resolution to the whole Ronin Nya thing would be for Ronin to become Samurai X, to still use the Samurai Tech that Nya made. It would be the final transition from Ronin being a masterless thief/mercenary to him being an honourable warrior, amd trustworthy ally. To see him leave behind his crooked ways - as we already have started to see - would be a really awesome story.

In the bottom left corner, there's a tall building that sorta resembles Borg Tower, from Season 3. Perhaps it's an indication that Ninjago City will be uprooted by Nadakhan, which means that he has some serious power. I really want to see what happens!

I'm more excited for the Samurai Cave, but I don't really see why there would be a Samurai, considering that Nya is a ninja now. Perhaps someone else becomes Samurai X? That would be awesome.

Not sure about the source, but I have heard that Garmadon will return in season 6.