The great part is even if you do not have the space for a garden you can still save seeds and prep them for long-term storage.
The reason some heirloom vegetables are back is that someone found decades-old seeds in a barn's seed room. They found seeds for plants they thought were extinct. Took a few years to get them back to the market, but they did it.

@TheHerrDark I understand that Norway is keeping a vault of heirloom seeds on one of their arctic islands in case of global catastrophe. That way they can feed the survivors.

@FuzzyMarineVet or a severe blight that wipes out whole crops

@TheHerrDark I believe that qualifies as a global catastrophe.