Bare in mind the footage we seen was a work in progress, something the narrator of the video repeated a few times, not to mention the watermark at the top.
I can imagine this WILL be the final, big top end AAA title for this current gen on PS4 Pro and Xbox One X, TLOU2 maybe releasing around the same time also. I can only imagine the devs have had next gen in mind and I believe this will be the first cross-over game which will be on both current and next gen consoles, next-gen and PC versions being the far superior, especially with the real-time ray tracing of the RTX on PC, game would look phenomenal.
As for having that many NPC's in screen space at once, all depends on how optimized the game is for the hardware to run it consistently at a respectful frame rate. As for the infamous resolution question, we will soon see on launch how it runs on current consoles.