I would set an annuity rate for the PF government endowment at 4.00% - no higher. If we succeed in re-balancing our economy, it may be possible to reduce the annual annuity take and thus increase the rate of growth of the PF Corpus. We can pretty much operate the PF in this way now - we don't even need to change things except for the potential decisions made by the Legislature.
The CBR, budget cuts, and new revenue will be in play to fill the rest of the gap. Of course I am assuming the Dividend has to end - sorry to be the bearer of bad news. Maybe some day I will be as widely respected as Ron and  Patricia Zobel!