Divided capital cities are a sad result of wars.  No capitals get divided as a result of peace; they are unstable models.

-divided cities make up less than 1/1000th of 1% of all cities in the world
-divided cities are almost all less than 50,000 people
-most divided cities are split by a natural boundary like a river
>> none of that is true for Jerusalem

The only rationale of dividing Jerusalem is that Palestinian Arabs have asked for it as a capital, which is the same as Israel asking for it.

Three of the divided capitals in recent years – Beirut, Berlin and Jerusalem – have been reunited.  The last city – Nicosia, Cyprus – is still under negotiation to be reunited.