In short, yes! We envision there being platforms that were made in some ancient, undefined era in each of the cities where people turn up. During the monster plot, Yennefer went around and pulled relics to redirect/protect cities, having someone stay behind to reinsert the relic once it was time to go.

In terms of getting more relics for a plot like this, we'll cover it in the future - but our idea for this plot has never been to remove current gates, if that helps at all.

Oh, and you just need four relics per new open gateway, which would then open up to other locations, too. So, you wouldn't need four new relics for each city.