In a full scale engagement, NATO's totally conventional resources are good for about two weeks. The only thing left in the resources at that point is nukes. The current engagements are piddling efforts and even that is straining the conventional resources. NATO's real "teeth" amount to the engagement of nukes. If they aren't going to be maintained in useful, deployable order, then NATO becomes toothless.
You cannot say how long Natos conventional resources are good for, unless you can specify the opponent. Full scale engagement with who? Russia? They are much weaker than they were in the cold war. China? They are a long way away - it would take forever for them to get to Europe. Nato's conventional forces could hold them indefinitely.
Nato's real "teeth" are NOT the engagement of nukes. If that were so, Al Qaida and the Taliban would have gone long ago. Force is useless unless it can be applied, and we cannot apply nukes against our current opponents. If conventional resources are being strained by the "piddling efforts" we are engaged in now, it stands to reason those resources need to be increased, because we can lose in Afghanistan, and lose big.