It looks as though the online multiplayer for Uncharted 4: A Thief's End may not be making its way to the upcoming PS5 and PC re-release.
Why Uncharted 4 is a Disappointment After Playing The Last of Us
Canceled Last of Us Factions standalone game: Multiplayer details, concept art, more - Dexerto
Uncharted 4 multiplayer may have been axed for PS5 and PC
20 E3 Games That Were Never Released
The Last of Us Part II multiplayer cancelled
New Details and Images Emerge From Uncharted 4 Multiplayer Beta, Due to Go Live December 4
Uncharted 4's PC and PS5 version removes multiplayer, ratings board suggests
Uncharted 4: A Thief's End New Gameplay Preview Video Showcases, uncharted pc gameplay
Standalone versions of Uncharted 4 and Lost Legacy delisted ahead PS5 collection's release : r/PS5
Naughty Dog abandons The Last of Us Online: what it says about Sony's live service strategy
Sony Significantly Scales Back Development of The Last of Us Multiplayer for PS5, Says Report
PS Plus Collection axed while the service continues to bleed subscribers - Mirror Online
Naughty Dog Ceases Development Of The Last Of Us Online - Game Informer
Nothing But Ports, Remasters, and Cancelled Games. What Has Happened to Naughty Dog? : r/thelastofus