"Shhhh....tuff Hitting the Fan," for me doesn't have to be a national or global collapse, because I have been in enough emergency situations to conclude that Murphy's Law prevails regardless. I try to gear my tools and mindset to that and it has served me well.
1) An emergency is going to happen.
2) It's going to happen when it is:
a) COLD;
b) WET;
C) DARK;
D)______________ fill in any other worst possible annoyance for the situation here.
3) It's going to happen when you're not necessarily expecting it ("emergent?")
Without going into EVERYTHING I do to mitigate potential failure in such a situation, I'll just say which lights I own for that purpose/reason. If the grid goes down long-term, I suppose I'll have to resort to cat tails and 'coon fat-torches or something. I'm thinking the weakness will be charging cells, and if I have to spend more time building a system and spending energy to charge with it, I may as well put the effort to something else. I had to learn to live without flashlights as a kid, and would have been subjected to non-judicial punishment in the Infantry, as a young adult, if I'd have been caught using one in the deep, dark forests of the Pacific Northwest.
So, to me, a flashlight boils down to being one really fantastic LUXURY I'd do without if worst came to worst.
Wile I dearly love the new stuff Sofirn is making, and I have an old Eagletac SP20, which is STILL an amazing light and a Gerber (formerly CMG) which gets used several times a day (night), EVERY DAY since they came out, I still don't count on them as my last-ditch lights.
In my emergency kits, I keep two versions of the Surefire L1 and a Surefire E2L with a KX1B head. Needless to say, they rarely get used, but for some reason, I trust them, which may be a mistake, but I don't know.
I perceive Surfires to be more rugged, reliable and dependable in rough conditions, even though my most-used lights have stood the test of some pretty brutal treatment over years. This may be a TOTALLY irrational thought, but that's what I keep for the knock-down, drag-out emergencies. I'd feel pretty stupid if I died because I swapped out my Surefire for a Sofirn.
I have been gravitating more toward AA cells, specifically in lithium and NiMH, and I keep a pretty good supply of either. I do have several "landscape lights" which will charge AAs (slowly) if it comes to that. Yeah, I have a generator, but it takes gasoline, and that's one of the things which will be "short" in a bad situation.
Or, cattails dipped in 'coon fat......
No, I've never tried that - I'm just making a point.