@abbot What @sergiusens is saying, in an arguably obtuse way 
, is that the “architectures:” field in snapcraft.yaml today defines exactly what goes into the respective field in snap.yaml inside the snap.
So if a single snap is built with, say, “architectures: [amd64, armhf]”, that will produce as an outcome a single snap that will be happily installed in both of those architectures. Unless the snap is indeed capable of running on both of these architectures (is independent, or has binaries for both), this is not what you want.
This is indeed a bit confusing and unexpected, which is why we’re changing that field to allow defining multiple architecture sets, one for each produced snap.
There are further conversations on this topic if you are curious.
@sergiusens Do you have more details on the schedule frame for this to land?