Be realistic! What great future is there for a small island? Just take a look at this
list of island countries and check out those with more or less the same land mass as Singapore. None of them are great, except maybe for Malta.
The only option for Singapore is to merge with some other bigger country. The advantages we can bring to the negotiation table are: Singapore's relatively good geographical location near the equator and in East Asia, well developed infrastructure (except maybe the MRT), and Singapore's younger population educated with passable English.
I don't think Singapore can merge back with Malaysia. I just think it's impossible. The differences are too huge. We can't merge with Indonesia definitely because Malaysia will not like it. Merging with Brunei, the Philippines, Thailand or Vietnam doesn't benefit us in any way. Merging with China will only invite hatred from our neighboring countries because of China's claim in the South China Sea, and most of us don't tolerate PRCs very well. Merging with South Korea or Japan will be hard because of the gulf in the languages. Merging with Burma, Bangladesh, India or North Korea is crazy.
So we are left with the English speaking countries to choose from. We can't go back to Britain because we know how inept the British are during the Japanese Occupation. It is also a dwindling empire, and the British accent is awkward and smacks of aristocracy. Merging with Australia doesn't really offer us anything in terms of security, and Indonesia and Australia aren't exactly good neighbors. Merging with New Zealand doesn't advantage us because we can't rear cows as a cash crop in Singapore. Merging with arctic Canada is meaningless because we can't bring their cold air to our tropic island.
And so we are left with the USA, and merging with the USA makes the perfect logical choice. The USA needs a permanent presence in East Asia to maintain its superpower status and to contain China, and Singapore offers it a good location to base its military presence. I am sure our ASEAN neighbors will appreciate it. But Singapore offers the USA more, not just militarily, but economically as well with our port and airport services. In return, the USA offers us their entrepreneurial culture and education system. I am hopeful that the infusion of American education and talents will transform Singapore into one of the the most vibrant and democratic cities in the world.