I don't think we are going to see a 4 carriage monorails anytime soon. Most of the stations don't even have a wide enough platform to support the length of a 4 carriage monorail.

The biggest setback has to be the monorail extension. With no proposal yet in sight, the earliest it will be up and ready for use will be post 2020.
If you take the LRT extension as reference, rumours of it first surfaced back in 2006. Our then, deputy Prime Minister, Najib, announced this together with the Transport Minister Chan Kong Choy. The proposal was finally made to the public in 2009, for comments and feedback with a target completion in 2013. Now, the target completion is slated for 2015. Hopefully, there will be no more changes to the delivery date of the LRT extension project. That's a good 9 years since it was officially mentioned by a government top office.

The monorail extension news is currently a shout out by a top management executive from a developer only. Assuming the rumours can be confirmed and PM gives his backing to the project tomorrow, if you add 9 years to it, that will mean sometime in 2022, earliest. Bare in mind, government has only mentioned about MRT line 2 and 3, and I think that will take precedence over monorail extension in terms of priority.