It seems like Weiss and Blake will continue going there separate ways for a little while at least, but I agree that they could have at least had Yang catch up with RNJR. She was so close...
Random thought - what if all of the RWBY songs are intended to have been written/sung by Weiss? We've already seen her perform twice within the story - the White Trailer and V4E6 both feature her singing. The Yellow Trailer also features a remix of Mirror Mirror. The interesting part about this is that the remix seems to be being played in the club - as in, Yang, Junior, and all of the patrons can hear it. (Unless I'm just making an incorrect assumption). Not a big deal, Mirror Mirror is already in the universe. Well, the Yellow Trailer also features remixes of Red Like Roses and From Shadows, as well as a version of I Burn. Ruby also listens to This Will be the Day at the beginning of the first episode. So the rest of the songs existing within the universe seems likely.
So what points to it all being Weiss? Admittedly, not much. All I was thinking was that most of them have Casey Lee Williams as the vocalist. This includes both Mirror Mirror and This Life is Mine while Weiss is singing them. Honestly, that's the only reason that I have. On the other side of the argument, I would say that the types of the songs seem a bit varied for what we've for sure seen from Weiss. At the same time, these songs are all made by the same people in real life, so that might not be too big a deal. There's also the few songs with vocals from Jeff Williams, which would have no explanation if Weiss were solely responsible for the songs.
I still think that all of the songs actually exist in-universe, for some reason or another. Whether or not it's all Weiss is something I'll have to look for more evidence for or against as the series progresses.
On a slightly off-topic note, is it still considered double-posting if it's been a significant amount of time?
Yes. Yes it is. - Slime