Well, to put a fine point on it, you are asking us to give an integer answer to an equation which is all variables beyond today's date.
They keep telling us we are looking aw world-wide inflation and currency issues. So, your question might be rephrased as "How many dollars ought I have on hand next year?" The answer above, f "Enough" is as apt for ammo as for currency.
The "they" reporting potential shortages ought be subject to a gimlet eye, and a grain of salt the size of a cow lick. Especially when a generic term like "gunpowder" is being reported.
See, my bros in the pyrotechnic entertainment field have been saying that there's a major shortage of both black and flash powder--mostly due to Chinese factories running at full tilt for NYE and Lunar New Year fireworks production.
Some of the news reporting has conflated that shortage of black powder for fireworks with the production of smokeless propellant for firearms ammunition. Sadly, the journalism trade now prefers things which create "clicks" rather than an informed audience.
Now, there are rather a lot of wars and similar belligerent activities going on right now--so there is demand for smokeless powder frim the finest grain size up to 1" diameter extrusions. But, that demand has been high for better than a year now.
The conditions and quanta on retail shelves is probably more due to Just-In-Time inventory schemes rather than world politics.
Watch the prices on retail shelves, buy when it's a bargain as often as you can afford--you will wind up with rather a lot, even 1 or 2 or 5-6 boxes at a time.