The most likely place to find Zorquan is exactly where Zorquan always was
The Outlands (and the Material, natch) still exist in 5e;¹ absent any further information on the subject, my assumption would be that Zorquan is still there, same as ever.
On the other hand, the Astral does indeed have a “graveyard” of floating god corpses in it,² and this is an area that is little-explored.³ That means it’s pretty much always possible to add new corpses to it without conflicting with any canon, because canonically no one has a complete survey of what’s there.⁴ Zorquan could be in there without us knowing. Of course, his absence in the Outlands (or Material, if you go with that) would be noticed—though that absence was plausibly not reported as far as us, the readers.
But Zorquan was old, even by divine standards, and fairly powerful. Zorquan’s death would not happen easily, or quickly. I wouldn’t take absence of evidence here to be evidence of absence.
Player’s Handbook (2014) pg. 302—note that the diagram on pg. 303 doesn’t seem to show it, but it is there.
Tended to by the Guardian of Dead Gods, formerly known as Anubis. Deities & Demigods (1980) pg. 45. Note that later editions of D&D have just put Anubis in the “Pharaonic” pantheon, but this pantheon isn’t really used in official campaign settings. Even in the Forgotten Realms—where the Mulhorandi pantheon was the Pharaonic pantheon allowed into Toril by special dispensation from Ao—makes a point of Anubis not coming with,¹ to leave him available to become the Guardian of Dead Gods.
- “Hate of the Cobra” (2005)
Largely due to the aforementioned Guardian, who is very high on the “not to be messed with” scale in the D&D multiverse, much more so even than he was as Anubis.
Except, maybe, the Guardian, but if he has one, he isn’t sharing it. The githyanki famously built thea city of, Tu’narath, on one of these god-corpses,¹ as have others,² but even they don’t know the full extent of the graveyard.
- Mordenkainen’s Tome of Foes (2018) pg. 91-92, most recent among many sources.
Mordenkainen’s Tome of Foes (2018) pg. 91-92, most recent among many sources.
Spelljammer (2022). Note that this book contradicts basically everything about its subject matter as found in prior editions, and should be viewed—apparently in its entirety—with extreme skepticism. No one needs a spelljammer to explore the Astral.
- Mordenkainen’s Tome of Foes (2018) pg. 91-92, most recent among many sources.