The way manufacturers are going is to forget about SD cards and exapandable memory.  Apple have always done it, Motorola Nexus / Google did away with it, and I think it was written into the contract for  Hewuei (SP) Nexus 6P to name but a few.  After the 3G iPhone mobile providers decided to do away with unlimited data on contract phones and to charge an arm and leg for data. So streaming is out of the question to an extent.

So Spotify, if we are on the above phones and looking to expand the memory via OTG will there be support for this in the future.  I have a 32GB Nexus Motorola, I like my music, I like Spotify,  I like the community, I like the features, what I don't like is not having the option to put the cache offline files where I want them to be.  Internal memory is the only option.

Surely, in this day and age, if Spotify can read off an Ext SD Card, then surely it is more than possibile to read off an OTG USB Flash drive, Pen drive, OTG USB SD Card, OTG WiFi Media Storage thingy using only the Spotify App.  If I can stream a movie off my OTG Flash Drive using MX Player Pro stored on internal memory, then surely Spotify can do the same.  Come on all those paying for premium per month, it can't take that much to develop or tweak exising software.