The country did move towards a common identity. NS also helped speed that process when the dialect platoons were disbanded. You could sense it in the air. It was not PAP's making but something that evolved as both Malaysia and Singapore prospered and grew in the 19th and 20th century.
PAP did help by building the economy which brought unemployment to zero. Life was a bliss. A good example is the nightlife of 60s, 70s and 80s. Bands were multi-racial, one had friends of many hues, visiting one another to celebrate the various festivals was a common practice. Even things like kite-flying, football, badminton had multiracial teams across the age groups.
Then came the Mandarin speaking campaign, followed by the SAP schools, the line in the sand began to emerge, Muslim fundamentalism compounded the matter and now truly fucked. The class conscious Northern Indians will not break bread with the low class southern Indians unless they are Ministers, MPs etc, the PRC are here to make best use of what Singapore can offer from scholarships, Hawker centre opportunities to brothels to service clients. The Ang Mo is again top dog and spitting in our face.
And a moron of a prime minister who thinks that Singapore is for everyone. Arsehole.