Spotify is replacing the former use case for me (Google Music is currently not available where I am), but the second stands.
--edit-- Also I'm loving the phablet form factor, which is keeping me on non-nexus at the moment.
OTOH the use-case was pretty plane-specific, and you don't often need a phone on a plane. Perhaps a 7 inch tablet (to replace the kindle) would suffice. Though then we run into the same problem, the Nexus 7 has no SD slot either!
(personal experience, probably different for other people)