Download times and storage aren't the common consumer issues they once were.
The only things keeping WMA in the works are the time as well as expense of converting to .wav or similar, (IF the original files weren't kept), and maintaining the allure of the more expensive Audiophile version, (which, in reality, would be easier, faster & therefor cheaper, to have set up as there wasn't the time & expense for conversion to WMA).
A 320 MP3 guitar track in a mix might be hard to distinguish/pick as lower resolution than a 24bit guitar part but there are some complications that occur after conversion & further down the mix/stem/master chain such as dither and noise shaping that can be a problem for the unwary particularly if starting from a low res "lossy" format

Cheers
rayc
"What's so funny about peace, love & understanding?" - N.Lowe