Naturebest, you are completely right... The jam can only get worse in the coming years.
But the real catalyst in Nusajaya will be the High speed Rail station from the Singapore - KL link.
It has already been disclosed that this line will have a station in Nusajaya (my speculation is in Gerbang nusajaya ).
Imagine the following: you live in your lovely landed house in Horizon Hills, east ledang, leiure farm or on your beautiful condo in Puteri harbour &Medini.
You take your malaysian car (several times cheaper than your a similar car in singapore ) and you drive to the HSR station (5-10 min bases on your location in Nusajaya)
You now park in the HSR station and take a wait for your train to singapore marina bay (10 min)
You are now in the train for 10 minutes.. Yes.. You have your own seat and you can play your computer/ipad or read the newspaper during your short journey to singapore CBD.
You are now in marina bay station... Allocate 5-10 minutes for your final destination.
Shortest time: 5 +10+10+5= 30 minutes!
Average time for nusajayan: 10+10+10+10=40 minutes!
The above calculations are door to door i.e. you leave your nusajaya home at 8:30 and by 9:00 you reach your office desk(shortest route.)
All this by 2020... The above times can match travelling distances from central singapore to singapore CBD and are much faster than suburban singapore to CBD.
So, the bottom line is... If HSR is built, it's a non Brainer moving to nusajaya.
As for the discussion of Nusajaya vs JB city.. My opinion is clear : nusajaya .
I am ang moh myself, and believe me, there is no way I am going to make a single step in JB city...my malaysia experience will be limited to: Horizon hills, Ledang, Leisure Farm, Puteri Harbour, Medini, Gerbang nusjaya and Sunway Iskandar and the Internstinal Destination resort.
It is a free world to own multiple property any where n is up to us to decide where to stay. If Wugi can hv the solution to ease the jam during peak n improve the crimes issue, I might consider to stay in Johor. I doubt both govt can anything further.