The idea is so simple to explain :
As it works for External / Remote Containers since FileMaker 12, i would like to see in future version a possible externalization of all other data type.
I expect a so versatile system we have for containers that allow embedding or externalizing the data on demand.
Thus, it would be a real data separation tool where ALL the logic could be stored a part of the data itself and facilitate the deployment update of your solutions.
Actually, Data Separation Model works quite well but have a great time cost and worse, some features have to be let down the road for many reasons.