Spoiler:
The cover is indeed accurate, saw it at my LCS today. I wondered why there was a new Sentry book out I'd never heard about, then realised that it was the Fallen issue that has been kept so secret. I didn't pick it up though.So indeed Sentry/Void does indeed bite it in Siege #4. As does someone else seemingly...
As we've seen, Void is putting the beat-down on the heroes, Loki uses the Norn stones to power them up and they start hurting the Void. Loki then takes the stones and sacrifices himself to destroy the Void... only for the Void to regenerate and survive the attack. Now without the the stones, Steve asks Osborn how to stop him, Osborn replies they cant and that the Void is The Angel of Death.
Tony then uses extremis to take control of the still smoking Helicarrier and tells Victoria Hand to evacuate everyone off. Shellhead then turns it a giant bullet and smashes it into Void, detonating it on impact. After the smoke clears there is a giant crater, with a naked Robert Reynolds (now with short hair again) lying in the middle. He asks if he did this, which Tony confirms. He then tearfully begs the heroes to kill him, to which Thor refuses, saying that he will live to pay for all that he has done to Asgard and The Avengers. Bob then transforms into the Void again and begs to be killed.
Thor then strikes him with a massive bolt of lightning killing Bob/Void, only leaving the fried remains of Bob's skeleton. Thor then takes Robert's remains, flies out to space and throws them into the sun.
That isn't were the issue finished though, but I wont reveal that here, may so on the Avengers Spoiler Thread though. So yes Sentry (and Loki) are seemingly dead.
end of spoilers
i guess this siege #4 spoiler. Just found it