There's also Bolivian Rosewood, aka Pau Ferro, though I don't know what its janka rating is. Makes for a decent fretless board though.
I wonder if we'll start seeing a rise in composite materials. I know some manufacturers are playing around with phenolic/ebonol boards but I've seen only two that offer it on sub $1000 basses (Wolf and MTD). Personally, I would love to have a fingerboard that is as hard and looks as good as ebony that isn't actually ebony. If phenolic boards are just that then maybe that's the way to go.
i have one instrument with an ebonol fingerboard: i like it, but it seems to 'react' exactly like my ebony board: apparent wear. i'm not complaining. i have #2 rosewoods, one ebony, and the one ebonol. i like them all, play them all, and haven't been concerned about the wear and tear. i agree that "maybe that's just the way to go."
(i'd snatch up a fretless jazz style neck with an ebonol fingerboard. can anyone point me?)