There is no One country the rest of mankind cannot live without, its reinstating what it were before its becoming, and the world had progressed without. The worth tat these countries are known for, turns into opportunities that simply gets displaced.
The World can certainly live WITHOUT Singapore.
Singapore's population is too small for any marketer to be interested compared to neighboring countries with larger population size - which leads to our Singapore Government being the most vocal and pro-active ASEAN member to push for Regional Joint Projects and a Common Asean Market.
Its working population is also the highest paid in this region, although the population is best educated the resourcefulness of the workforce is open to question. There are neighboring countries whose workforce is as well educated and as resourceful as Singapore - if not more.
As a Manufacturing Base, it does not have any competitive in labor, land and utilities compared to countries with a larger land mass.
Can our success be sustainable in our effort to be a hub for Air Travel, High Finance, Bio-sciences and High Tech Industries ? Will countries in the regional grouping and further away unlodge us from our present lead position ?
In Regional Defense Co-operation, without Singapore's existence, the larger powers will simply find some mutually satisfactory arrangements in some other form of defense tie up with our immediate neighbors.
Singapore is a small and insignificant dot on the map, and we will need to constantly be on the run to stay relevant and also to plug ourselves to the Global system in order to stay relevant.
Sadly, the world can live without Singapore.
The world itself is a complex dynamic system with exchange of goods, money, information, energy and flow of people. Some dynamic changes are localised, some dynamic changes are regionalised, and some dynamic changes are globalised. It is self-sustaining.
The world will be different without Singapore. The world won't stop functioning. The role played by a missing country can be taken over by another. No country is irreplaceable in terms of that.
However, the flavour of life might be different, but such things merely dictate our preference. Lack of spicy food won't kill. Lack of food kills.
Can the world live without Singapore?
Answer: Yes, and watch it.
In fact, planet Earth would be so much more better off, without us humans around.