Before BvS came out, I was not worried about Suicide Squad. Now...
And yet, I'm still invested in Suicide Squad and it absolutely has to be good. It can make up for BvS, I think, if it's awesome.
I'm not too sure about the rumor. We'll see. I actually wouldn't mind more humor at all. Say what you want about the Marvel formula, but it works. I do like it. I've enjoyed the MCU, for the most part, so I don't think it'd be a problem.
We need to remember that humor doesn't negate a dark tone. See Daredevil or Jessica Jones... or hell... just look at The Dark Knight. A very dark movie that also had some pretty humorous moments, especially from the Joker. Suicide Squad has the Joker and Harley Quinn. I think humor is a given. And more humor isn't a problem as long as it's done well.