Bob Harras had something planned for Yellowjacket, something other than just her apparent demise. That strange armor she wore at the beginning of AVENGERS: THE CROSSING was the biggest clue. It looked nothing like her costume, which she wore when she stepped into the time stream to go back home in GUARDIANS OF THE GALAXY #60 (which was published only a few months prior to the Crossing issue, well after the plot of the Crossing was crafted.). I suspect that Rita made a pit stop prior to the beginning of AVENGERS: THE CROSSING and obtained the armor during some "lost" adventure that Harras/Kavanagh would have written had the crapfest that was HEROES REBORN not derailed the whole thing.
The potential for Rita to still be alive is right there, waiting for a writer to take interest. The Rita we saw killed could have been a Space Phantom, or we could see Rita pop up in the present prior to her death and have adventures until it was time to send her back to her death (sort of like the Mar-Vell situation).
If you're interested, I wrote a fanfic story called YELLOWJACKET: THE CROSSING, wherein I brought Rita back to life....and yet killed her off at the same time. You can read it here:
..it could have merely been a timestream variant Rita who died (look at all the variant Kangs who were created by his time-hopping habit). I loved that costume she was wearing.
Anyway, we need to start a Rita DeMara Appreciation Society and get Rita revived! I'll picket outside of Marvel's NYC offices, since I'm here.
And the Melter will be next!