I don't think having so many interchanges is good, end up waiting time + walking time for transfer will negate the time saved from having more train stations. Like how my journey from East Coast (my school) to AMK (my house) was only cut by around 15 minutes after Circle Line came out, despite the journey from Paya Lebar to Bishan/AMK MRT being cut by quite a significant bit.
There was a movie many many years ago depicting the situation where oil is scarce and all vehicles except public transport is completely banned on roads. This might be the solution to travel in the future!