Possible Mermaid Powers & More? Lets speculate

I could see them bring back the Singing skill from CI, or giving mermaids some cross-pack synergy by having them level up the skill much faster. It's not the most glamorous "power," but it'd be a fun detail.

Then again, it'd also be funny to have a mermaid with a horrible singing voice. But if they go with the power tree system, that could be a weakness.