I'm not a MOBA player and I find it pretty ridiculous how many games in that genre are already out and/ or are still yet to come, however I think one could still create some casual but fun experiences in that area.

What I imagine is for example a top-down tank based 5v5 or 7v7 MOBA, without item(s builds) but some abilities, or battle ship based (modern/ antique) with small islands as obstacles.