One of the previews shows him taking out an army by himself so we can expect crazy shit like that.
One of the best things about Aku as a character is how versatile he is and how his comedic aspects blend well into the really horrible shit he does.
Like the episode where Jack starts to become Aku. It all starts with comedic shenanigans, with Aku being affected by a cold. But then he just sneezes at Jack, and that comes the closest to actually killing him than anything else in the series ever did. And then later we see him brutally attack those monks and rant about how he'll devour them all.
Or the Jack and the zombies. It starts with a grumpy Aku just whining at his throne. But when he fights Jack there is that intense sequence of him chasing across the entire graveyard and going for the kill with that manic look on his face.
Aku is funny but he's not treated as a joke, his funny moments just make it easier for us to forget that he's one of the most powerful and evil villains ever put in a cartoon. Everyone forgets this is a demon that crucified dogs and reduced villages to rubble for kicks. And this, ultimately, just makes his eventual evil deeds have a much greater impact.
I'm expecting some really dark shit to happen, especially now with the mature rating