Tmobile has stated they will throttle, but only for customers using bittorrent and other P2P.
I will admit I've done that some on my phone, but only over hotel WiFi, I subscript to usenet anyway.
I'm only allowed to tether 5gb on my plan, but that's been enough (this month I'm at 14.5gb total, top users play music 3 gb, podcasts 2.5gb, tethering 2gb).
If I didn't have unlimited, that 14.5 gb would have been far lower, I only use wifi to control my chromecast when my tablet isn't in arm's reach.
Certainly all the podcasts, and most of the music would have been wifi.