That would require a massive amount of people practically living in the permaculture forest indefinitely.
It might work but it would be a major cultural shift and I have difficulties seeing that happen intentionally as some sort of targeted intervention and not a result of some sort of relatively mild collapse...
Maybe there could be a global climate service (similar to mandatory military service in some countries), where all young adults are working for 2-3 years in such a large scale permaculture effort? Might work, but difficult to implement sustainably and without force.