After googling a little, I came across this. From the Gold Coast council, draft plan from last year for changes to the Welches track.
Click here Its a PDF, but if you type "downhill" or "bike" in the search box, you'll read what their plans are.
It may be possible now that this is deemed DH'ing is a "prohibited use" of the tracks there, so be aware of that.

Anyone know if (as per the quote below) Wongawallan Road and Caballo Road have been closed as yet, are there any signs in place?
Quote from that PDF
A12.1
Close and gate Wongawallan Road and Caballo Road to all vehicular traffic except management and specially authorised vehicles. Such closures will be temporary
road closures under the Local Government Act and will take effect over tracks labelled a, b and c on Figure 2. The locations of locked gates is shown in
Figure 3. Mountain biking will no longer be permitted, but horse riding and bush walking will remain permitted uses following road closure. Horse step-overs will be
provided and gate keys will be issued to management and other authorised personnel.
Priority:High Time frame:1 year
A12.2
Dismantle and close the downhill mountain bike track which follows Wongawallan Road from the border of Scenic Rim Regional Council through
Eagle Heights Conservation Area and down to the bitumen surface of Welches Road.
Priority:High Time frame:1 year
Cheers