The real question the lady should have asked about what the watch can do is play songs from Spotify without your iPhone near you, like when you're running.
I have a series 3 and I got a beta from spotify to stream music, it worked with WiFi and the phone turned off. I haven't tried LTE as I haven't enabled that, but I suppose it should work fine.
Ugh. Bad commercial. Apple deviating from their dystopian earnestness rarely works out. Federighi sort of pulls it off, and I suppose the old "I'm a mac" commercials managed.
You are correct, Pandora's app does have offline support in the apple watch, and I just got a beta in spotify where I can stream music from wifi in the watch to a speaker with the phone turned off.
Pretty sure Apple doesn't expose the correct APIs to allow this on the GPS model of the watch - at least that was the case when I last researched this.
I searched a bit - I think you're correct, and also offline support looks to be in beta in the Swedish version of Spotify, so maybe it's actually coming at some point.