An example (with a lower density though) that we can study is Toronto. Like Singapore, Toronto is around 630km2 and has a CBD that is skewed to the south with a large natural waterbody. The airport is on the extreme west of the city. 2 main subway lines serve the city, combined with a combination of commuter rail and streetcars.
As Toronto is an amalgamation of several settlements, it has led to the development of a few "city centres" outside Toronto City Centre itself. The gridded layout and the metro system (especially the Yonge Line) has catalyzed the decentralisation of the city. Some of the major centres include North York City Centre 15km on the north, and Scarborough Town Centre 20km on the northeast (near industries).
Other commercially successful centres that have sprung up around metro stations along Yonge Street incluse Yonge-Eglinton and around St. Clair TTC Stn. Although not officially part of Toronto City, Mississauga Downtown can also be considered a major satellite commercial centre at just 20km on the west and close to the airport.
The success behind North York and Mississauga, and partly Scarborough, was the automonous nature of these city centres. These centres are essentially managed by their own city councils (before amalgamation). Hence each city centre have their own niche markets, as well as services for the immediate community.
What this means that for every services that Toronto has, are available in these city centres too. This of course include branch offices of banks and financial services, as well as firms such as consulting, design, engineering, pharmaceuticals, IT and computing, etc. Some of these firms are attracted to these city centres due to the catchment, and the employment base (young professionals who buy the new homes around these area), while for others it was a natural move to set up companies in their home base.
So one important issue for decentralisation to work in Singapore is that - are we ready to allow for each region to be developed autonomously? This includes identifying niche markets each region will concentrate on, and have each regional centre working on their own ways to attract commercial services to their "city centres".
Take architectural consulting for example, today architecture firms tend to congregate around the city centre, with most smaller firms in the Tanjong Pagar and civc districts area, and bigger firms dotted in Raffles Place, Orchard, Marina Centre, Bt Merah and Novena. In the decentralised model, either each "city centre" may provide opportunities are office spaces to be develop for architecture firms of various sizes, or one of the city centre may identify it as one of the niche areas they will develop. A portion of the firms may then decide to relocate due to the lower rents and possibility to attract young architects and engineers staying around these areas.