Well, Hilde hasn't been confirmed dead, explicitly, BY NAME, but Father Maxwell said Duo Jr's mother 'died' and Hilde raised Jr and is probably his biological mother, so it isn't much of a stretch. The latest date we see Hilde at is MC0017 NEXT WINTER, which you'll see in Chapter 8; the 'current time' is MC0022 NEXT WINTER. So she could definitely have died between then and now.
By the way, even though I haven't fully finished writing up the various synopses for the chapters that aren't released yet, I did update the Mars Century timeline on the Gundam wiki:
http://gundam.wikia.com/wiki/Mars_Century
It should at least give you a gist of what is going on. The other pages that will have the most info are Katherine Winner's, Hilde's, and both Duos', off the top of my head; but I still haven't finished updating the latter 3 yet for Chapter 8.
On another note, REI just created a gallery collecting all of her Wing art from the past year+, including some stuff people without pixiv accounts couldn't see before. Enjoy!
http://oz2union.sokowonantoka.com/gwgallary/index.html