All the DrawableComponent.Draw function does is call the actual render code. I haven't written that ECS myself, it's taken from the codebase of Almirante Engine.
Also, since RenderComponent is the only DrawableComponent (at least for now) I'd only have to replace a single line of code.
RenderComponent.Draw always calls the DrawModel function, which in turn calculates the world matrix, sets the shader and it's resources and calls the Draw function on the model itself (using SharpDX.Toolkit)
Moving the dependency to a system would be pretty easy if nessecary:
Create RenderSystem class, inherited from EntityProcessor or ParallelEntityProcessor
Set it's Filter to RenderComponent
Put in code to:
1. Fetch data from entity
2. Call render code and pass the data to it
Done.
I've modified the base ECS code a bit already. I could remove the DrawableComponent base class and have Drawable stuff handled by systems.
