I hadn't considered a BOB to be able to supply food and water for very long and not be something that I need to haul in a truck.
But your post got me thinking ....and while most common equipment choices are good ...they too are not truly very "sustainable" as I wouldn't have packed cases of batteries for the lights etc.
SO in evaluating what any of my own BugOut supplies actually do for me I arrived at the believe they can provide me some minimal tools and sustinance long enough to acquire replacement sustinance and tools to maintain or improve my minimal shelter etc.
Some of my kits are not yet really good for any longer than a few days. NONE have enough toilet paper to last a month ... and I learned as kid that I won't ever like wiping with myself with leaves ....but by having a minimal supply in my bag I put off the need to solve that problem the first day or two. I think a lot of the stuff we stash for any scenario pretty much does the same thing.
Its not perfect ...but at least I shouldn't be the one of those that has nothing the morning after the hurricane blows thru or the day after the ground stops shaking and is waiting for the gov't to save me.
And with any luck I can also defend myself from the looters that were too stupid to prepare in any way what-so-ever or at least take some of 'em out in their attempt.
But this thread has lit a spark of interest in selecting items like solar powered stuff etc that might provide utility for a longer term.