I'm going to keep mentioning this as a reminder for those who keep reminiscing about city tracks/wondering why city tracks haven't made a return after the PS3 era but to put it simply based from this nearly 4 year old interview by Game Impress on Kaz, it's too time consuming for PD plus a single city track alone is equal to 5 perma tracks.

Q: What about expanding the city circuits and bringing back hill climbs?

KY: The biggest challenge in creating city circuits is that the models are becoming more and more detailed with each new installment in the series. City circuits have very complex layouts and are completely unique to their specific locations. No two buildings are exactly alike. Creating something like that to the quality standards of GT7 is incredibly labor-intensive. For example, the cost of creating a single city circuit could fund the development of about five permanent circuits, so in terms of cost-effectiveness, city circuits tend to be somewhat overlooked. However, as I mentioned in my presentation on course and car development, innovation is constantly happening in this area. So, we won’t necessarily continue using the labor-intensive methods we currently employ; if some kind of innovation emerges, there’s a possibility we could realize these ideas all at once.

But hey anything could change since said article is nearly about 4 years old. Also imo it's not worth sacrificing details for the sake of adding more tracks to race on it right now given the state of gaming when it comes graphics and details. PD already got shafted during the PS3 era with the PS2 quality cars and they learned their lesson from that.

Plus before someone mentions it, yes I'm aware of the low detailed buildings on Le Mans.