Many central banks use fan charts and other devices to highlight such bands of uncertainty about the forecast, and the Fed should do the same. It would provide a better sense of the likely direction of policy and the variables most related systematically to that policy.
The resulting rise in the federal debt could drain funds away from private capital formation and thus over time slow the growth of living standards. Favorable productivity developments, of course, can help to alleviate the impending budgetary strains, but no one should expect productivity growth to be sufficient to bail us out.