Nothing is going to happen to the platforms and tracks at clyde because there is no benefit to removing them. The level crossing will be closed but nothing is going to happen at the station. That drawing you posted is not official policy transtopic but someones drawing about what should happen. Why would any rail organisation remove the points in to and out of clyde yard for instance which is used to store freight trains in the peak hour curfew periods. Regardless of what some people think you aren't going to get 2 more tracks between homebush and granville.
It looks as if someone has just taken the official sydney trains document and modified it to show there own plans.
I never said that the drawing I posted is official government policy, and it obviously isn't, but it is nonetheless an official draft planning document prepared by TfNSW, so it gives some indication of the thinking at the time. There may well have been other draft proposals which have not come to light. It's not just someone's drawing about what should happen, as you put it, as it is part of the planning process to consider alternative options. This may have been one of many, but we'll never know.
The suggested removal of points into the Clyde Yard have only been removed at the Clyde end and not the Auburn end. In the latter case, existing crossovers with the Main and Suburban tracks have been retained as the new track pair at that point is in tunnel and passes underneath. There may well have been a reason for that for operational purposes, such as the existing Main Line tracks east of Granville continuing to be used by Intercity and freight trains, whereas the new track pair continue in tunnel passing underneath them to connect with the existing Suburban tracks between Lidcombe and Flemington. How can you be so sure that the need for additional tracks between Homebush and Granville won't be considered at some future date? Never say never, or you might end up with egg on your face.
I did qualify my remarks in suggesting that the document may not all be relevant in the context of the current closure of the Carlingford Line, but that it gives some guide to how things may pan out.