It's too soon. Young Avengers works when the Avengers are grown up and out of touch with teenagerdom. That hasn't happened yet, at all. Also, right now, Spider-Man is the young Avengers, and while the YA does come first, characters like Kamala Khan and Sam Alexander do fit the 'Homecoming' mold, and work better as Spider-Man contemporaries than Wiccan and Iron Lad. There's also the bit where Stature is 8 years old, so... come back in two phases?
I get YA is a really important book to some people, that that's how they came into the Marvel Universe, that they found a level of relatability there that was unparalleled. As much as doing YA now would serve those people, that generation of comic readers, really, I don't think that it would serve the MCU as a whole very well. I think the TV verse would be ready for it, but then again, I don't see the movie and TV divisions getting along enough to make it happen now anyway.
Now in 8-10 years, when Cassie is old enough to be Stature in continuity, it really shouldn't matter what else is happening, because YA is a really great place from comics and waiting longer would make it forever a continuity tangle, so that would be the go time, imho.