Would freezing ruin an emulsified broth like tonkotsu?
Freezing broth has no ill effects. I would think that you could just emulsify the fat by boiling the broth when you take it out of the freezer. Boiling it again will lose some liquid, though. Or an immersion blender could be useful for resetting the emulsion, if needed.

Your biggest worry is making sure the broth doesn't dry out in the freezer.
Make sure that the liquid temperature is around 35-40 degrees (room temp will do). To make it air-tight I'd recommend going with some sort vacuum sealer. This will keep it from getting freezer burned and losing its shelf-life/flavor profile. Also a good thing to remember is that glass doesn't do well in the freezer as it cannot expand.

I would recommend keeping your broth as simple as possible to allow for the greatest flexibility; Unless you're going to strain it, leave the aromatics out of the euqation until it's time to make your ramen because the more aromatics are exposed to heat the less you can taste them. 

You can also cook it down and add water later to take up less fridge space.