Well i dont think bitcoin is either of this .because 90% of the people use bitcoins for earning ,that is sell the bitcoins when the price is high.Bitcoins being used for groceries is not being widely used,if used in this manner will change the face of the earth in many ways.
Well if it has the ability to effect the changes you're talking about then it is a digital gold yet to be mined and refined for people to see its value. I think it's both digital cash and digital good because it's electronically operated yet has semblance of both cash(fiat) and commodity (gold).