Can you make chocolate fondue without cream?
I have periodic trouble with lactose. My solution is Coffeemate, of all things, but it really works great and would certainly taste far better than soy milk for your purpose. Just boil a small amount of water, whisk in a lot of coffeemate, then whisk in water to the appropriate concentration. For more richness you could use a little melted margarine whisked into this solution. I use the plain Coffeemate and water that for making hot cocoa with sugar, vanilla and cocoa powder. For cream soups, gratins, mashed potatoes - savory dishes, I do add the additional bit of margarine.
Coconut milk has some natural emulsification abilities, but no where near the emulsification provided by the proteins in cream.
I'd add a little cornstarch to help prevent it from separating and I'd be very very careful not to heat it too much. If it accidently comes to a boil, I think you'd be guaranteed an oil slick on top.