Just keep a box of caffeine pills in your emergency rations. If coffee is unavailable, then use the pills to give up the habit, by reducing dosage every day. No headaches or other side effects (apart from missing the habit of making a coffee).

I bought caffeine pills when I went on a multi day hiking trip, because I was really worried about withdrawal :-) In the end I didn't need them, one cup of coffee I was able to get in the hut in the morning was enough.

The Mount Hagen single instant coffee packets are pretty decent and light if you're boiling water on the trail.

Switzerland has a strategic coffee stockpile.

Of course every country has stockpiles of fuel and grains.

I find the thought of a strategic coffee stockpile pretty amusing :-)