Google Play music has upped it's limit to uploading 50k tracks instead of 20k. This may take some time!
It's still annoyingly hard to upload .pls or .m3u playlist files.
And I still find it hard to understand the benefits of uploading your music to the cloud so you can download it again, played through a web music player that's a lot less effective than a local player.
http://www.engadget.com/2015/02/25/google-play-music-50000/
That would leave some people with a handful of files to upload in case they are not on record.