It's a whopper document, must admit I've only scanned parts so far...
My view is that it's better for everybody for mtb'ing to be managed than unmanaged. The solution for the Mt Wellington tracks is a good case study and has worked well IME - some paths shared, others out-of-bounds to bikes, and the new North-South track which is designed to attract mtb pressure from other areas... I kinda doubt that new areas will be opened up to bikes - the tide has been going the other direction for quite a while - more likely some existing tracks will be 'upgraded' to better suit and cope with mtb use, while others will be out-of-bounds and access controlled more tightly. That said, I haven't read the full plan... but a glance at the Overview seems to confirm it's more about branding existing 'trails' than anything else.
At the end of the day, mtb'ers will have to accept that the tradeoff for legitimacy and improved facilities is leaving other areas for walkers to enjoy. A bit of mutual respect and consideration works wonders

Matt -
who doesn't like being abused by walkers when riding, and doesn't like being buzzed by mtb'ers when walking