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I'd be very surprised if that was the case. They're streamlining the software and adding new streaming features (integrating Tidal for instance) but local libraries still seems very core to the offering and the new software that they're releasing. Moving away from local libraries would probably kill Plex as a product.
They got some stick recently for discontinuing their home theatre software on PC (their thinking being that you were most likely to have a mini device like Firestick, Roku, Raspberry Pi, Xbox, etc plugged into the TV rather than a PC) but they reversed that decision after lots of complaints.
Plex seems the obvious:
Plays back original or transcoded depending what you choose in settings;
Supports podcasts and chromecasts;
Allows multiple libraries;
Has an app on pretty much every device out there which works locally or remotely (and allows syncing for offline play as well).
FLACs aren't stored in the cloud but they can be accessed from anywhere so I don't think it makes much difference unless you have poor internet at home. If you really want a cloud solution you can set up Plex on AWS or Digital Ocean or something but it would probably work out pricier than a local solution.