Time will tell...
A new Destiny 2 datamine suggest the reappearance of the Cosmodrome location in addition to the Thunderlord Exotic machine gun.
First, datamined audio (courtesy Dox_au, below) has the Festival of the Lost’s host, Amanda Holliday, referring to the original Destiny‘s first location: the Cosmodrome.
Holliday references the area you first met your Ghost, and also speaks of Old Russia — as such, it’s likely a quest line in the Festival of the Lost will take us back to said area. Exciting, much?
The Thunderlord Exotic machine gun is a little less certain. Players have noted a new classified Exotic weapon in the game’s Collections area after the game’s 2.0.4 update. That, alongside the in-game appearance of the Thunderlord’s perk, Feeding Frenzy, has lead Guardians to be hopeful of the weapon’s return. Time will tell, eh?