Yeah, more Splatoon amiibo would be nice, though I'm not entirely sure who's left to make amiibo of, exactly (maybe Judd, like you said, maybe Callie & Marie, perhaps an Octoling, or maybe Cap'n Cuttlefish). Though I'd be more interested in what content you get from these hypothetical new amiibo. More single-player challenges (like, actual challenges, not "go through this level with a Charger/Roller/INVINCIBLE KRAKEN and a meaningless time limit since Kraken) would be nice, I'd be alright with that.
I'd go for them if Nintendo made any, assuming they had good extra content on them... Actually, I'd get 'em even if that wasn't the case, since they'd probably have unique gear on 'em and I want that.