One gun for all? Not for me. But for the sake of the post......
I'll run my SCAR 16s/ACOG+ RMR and a Gemtech Trek as primary. It's my survival rifle as all the neat hiding spots on the rifle have been filled with survival equipment...Just in case. Great for larger game if needed...carry 500 rounds-rig and pack no problem. No need for tons of ammo, surviving is about conservation and avoiding trouble.
What really will happen:
I will also sneak a Charger 10/22 in the pack with a threaded barrel, 100 rounds of SS and a box of federal bulk.....comes in handy
Rem 870 in the scabbard 50 rounds, baggy of 209 primers, and 1lb blackpowder.
S&W M&P Pro 5" on the hip, 5 mags, 50 rounds spare.
Even with my survival kit this all weighs less that what I've humped around places with zombies that shoot back.
a flamethrower and flaming swords you might as well use a flaming potato gun. you give a close combt enemy a bit more of a ranged weapon. but at least the walkers would have a warm meal for once.