Grayscale/Color dynamic input node

I really want an input node in my custom graphs that acts as the input node on the levels and blend nodes. A node that dynamically detects the input type and then outputs grayscale and/or color if needed.

It would save me a lot of hassle when building custom nodes if I don't need to make them using a boolean to toggle input and output visibility. I just want run everything though the same graph, independent of input type without using conversion nodes.