Makes sense. The world moved on from Unreal Tournament for better or worse. You can't just release and leave an online-only game any more. It has to be supported with years of content, or it's never going to be popular and make it's money back.
I'm going to guess it was always a small team ticking over in the background of Naughty Dog anyway. Their minute to minute gameplay is solid, but their stories and bombastic set-pieces are much more interesting and separate them from a crowd of pretenders.
There are actually still people playing the original Unreal Tournament from 1999 on public servers. I occasionally jump on one of them and it's still the glorious chaos it always was!
Yeah, it's still there, but it's from a different era. If Naughty Dog could make TLOU Online for $2 million like UT was developed for, they'd have just done it. I suspect they've spent more than that just on market research, and the answer has been "gamers aren't really interested".
I mean, I like the TLOU and Uncharted games, honestly don't think Naughty Dog has ever released a bad game since the PS1, but I can't see my self playing some online multiplayer only bullshit version of it. The players that do want that have already got enormously successful games that they already play. Muscling one of them out of contention seems like a monumentally hard task for a small team to do.