The question is, do you want to create a one-time arrangement with a collection? Or do you want to create an arrangement that then needs to be modified or influenced by other modifiers in the modifier stack?
For the first thing, Empty elements in 2.8 support collections instances. You can create the instance with an empty. Array modifiers do not support Empty elements, but you can use the following addon with the empty:
For the second thing, there may be some limited and tedious Workaround there. I don’t think developers will add new features to Array modifier, so we will have to wait for everything nodesd project to be completed and fill the Array modifier shortcomings.