While in the past, the Singapore river was used as a commercial and trading route for the settlement. Many Warehouse were built in the area but they are now converted into shops that sells souvenirs.
The river also used to be able to allow people to swim in it but now it is terribly filthy. Basically this place is converted into a tourist attraction to increase income for the country.
I believe that the shape course of Singapore will not change or only change by a little bit. This is because the banks are all made up of concrete and as this is a tourist attraction now, the government will certainly be monitoring it and will do measures to prevent drastic changes in the river shape course. Hence, I think the Singapore river will continue it's shape course and hopefully the only thing changed will be the cleanliness of the water and the bad water quality of the river now.