Come again?. The have been 3rd party open world games that have had less npc's etc on console versions but have had options to have more on pc, so this is totally down to the developer if on release the isn't many npc's on the streets on pc and next-gen versions as other games have done it (But then mod on the pc version will most likely fix it if that's the case anyways). As for the street signs, if you think all next gen open world games are going to have different signs and posters etc on every street your mistaking that's nothing got to do with the hardware and more to do if the developer wants to put in them details. PS1 games etc could of had different signs everywhere if the developer wished to put in that much detail.
Not really. For example why do alot of npcs in game look the same? because of the ram and storage. There was a talk recently that talked about re using assets and how the ssd will make it alot easier to load up certain assets in areas without having duplicate assets making things easier.
Thats changing the subject since you was talking about street signs and not enough npc's on the streets, not how many of them look alike And trust me you will still see characters looking alike in open world games even next gen imo as its easier for the dev to "Re use assets" then make all new ones for every npc.