I've read that Steve Cole and Matt Sprange plan to wait 3-6 months, gauge market reaction to the minis line, then see if alternate offerings are necessary. So Eagle/Hawk series boxes may happen, but they won't happen for six months (at the earliest). In the meantime you may be stuck with swapping/selling your Kestrels to Klingons who want them.
I don't know if you could make a viable fleet out of Eagle series ships alone, they tend to be a bit small. The Vulture dreadnought is only about BCH sized in terms of points. And that's not even available yet. Hawk series fleets are definitely viable though.