it may be a little fishy to assume that what is essentially good luck will continue forward, for no reason.
but, i think that more than balances itself out with increased revenue from other sources.
but, this is a hypothetical on a hypothetical. pointless.
from a pr perspective, and what else is really valid here, the government should probably not be predicting budget surpluses or deficits five years in advance in the first place. that would shield it from hypothetical criticism on hypothetical outcomes.
www.cbc.ca/news/politics/pbo-fiscal-outlook-government-optimistic-1.3345113