At this point I think it's entirely possible they don't say anything about Challenger Pack #7. They have never revealed the next Fighter in one of these presentations, and considering the circumstances we've seen transpire with a major lack of announcements halfway into the month, I think it's possible we get the ARMS character in typical Smash presentation fashion, and that's it.
However, I think getting the ARMS pack out of the way for now may be for the best. Even if the wait itself goes until September, that's less time than the current transition from Byleth to ARMS, and in this time frame, we can play as the long-awaited ARMS character.
I've kinda...sorta...made peace with the fact that we may not actually get the ARMS fighter until June 30th. It sucks, I think that's lame to draw it out for so long with no transparency, but I think that could very well be what we're looking at.
As I said earlier, I'm usually pretty positive or optimistic. I just think Nintendo dropped the ball here. They were clearly hit harder than some other companies, so I can understand not being ready necessarily to promote or market games. That said, it shows a profound weakness is adaptability in such a scenario, and it's clearly a major one. They need to fix it.
I think it would be great if they closed out the ARMS presentation with some sort of transparency as to when we'll hear more about Volume 2, but for now I'll look at it as wishful thinking.