Cities merging does not need to mean identities merging, or getting a single city centre anyway.<p>I live in London suburb. I rarely go to central London. It&#x27;s close for when I want the amenities there, but it&#x27;s just one centre amongst <i>dozens</i> in London. Heck, my own borough, which is one of 30 in London, has at least half a dozen town centres with their own distinct identities. I&#x27;ve not even visited all of them.<p>I doubt that will change even with mega-cities. What is considered &quot;low density&quot; regions between the centres will just change. E.g. if you drive through London, it&#x27;s not like you&#x27;ll suddenly see farm land (unless you try to - there is some) in between the town centres - it is continuous urban&#x2F;suburban - but you notice when you come to a new town centre, by the increased density of shops, offices and non-residential side streets. The distinction is quite noticeable even in the inner core boroughs where the &quot;non-town centre&quot; areas may be residential high rises or large town houses instead of small terraced houses, but still noticeable different from the commercial and cultural centres.