Seedy Radio will probably return.
Would it work to build the station off whatever track is currently being played? Sort of like what Captain Kirk did when they put the Startship Enterprise into Warp Mode?
That would work for me. Looking at the main 'Player' menu, I see Play Radio, shuffle, and repeat. Both shuffle and repeat have multiple options. It doesn't mean the Radio should have 2 options, but if it did I would love to see them be 'Play this time only' and 'Play Always'.
The Play Always option would sit in the background waiting till playing now ended to start playing. It would hopefully persist across MC startups. Think of it like the Automatic shuffle option, its only there when needed!
It would also work for seeding, since you could simply just play one song at startup or whenever and it would base it on the last playing song.