Potatoes, sweet potatoes, turnips, taro, tapioca, those weird south american tubers related to Malibar spinach, and the tubers of runner beans immediately come to mind as long term storable calorie crops.
Of note, the consumption of flour has recently been pushed back to at the very least 32,000 years ago, probably much longer, even if field agriculture has not:
long term storable calorie crops
Doesn't that depend on the climate? I don't know for how long can you store potatoes and such in tropical climates -- my guess is not for long. If you are in, say, Northern Europe, the situation changes considerably.
Plus, the tubers you name are predominantly starch and people relying on them as a staple would have issues with at least insufficient protein.
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