Since this is in the NV forum, I assume any plans for a "SHTF" rifle would be heavily skewed toward nocturnal operations...
Personally, I'm looking at a night "ensemble" -- not only a rifle with important bits stuck to it, but also what I'm going to stick on my head as well to go along with it (not to mention other accouterments along with it, like armor, comms, brain buckets, mounts, chest rigs, hydration, IFAK, secondary arms, ammo, caliber selection, etc).
Maybe we can turn this into the "If you and your family had to leave your home on foot with one hour notice what would you -- personally, just you -- take?" thread. I know different states complicate this, so let's assume, for baseline purposes: semi-auto only, no mag cap limit, suppressors/SBRs allowed, NV gear must be reasonably / legally acquired / available (no black market stuff (i.e. "pre-owned" .GOV gear), but gray market is OK), along with what an average 6-foot, 200-pound man can wear and carry for an extended period.
The biggest problem I see is powering your junk for more than a couple of weeks. Ideally, I'd carry one of those foldable, portable 100W solar panels, a few 10K Anker packs, some 700mW CR123 rechargeables, maybe some BlackCube AA's as well, and not worry about having to find and carry too many extra batteries. The new breed of high-discharge Li-On rechargeables handle all of the latest NV/Thermal gear just fine and get great run times to boot.
I'd grab my ENVG/FWSI setup, but that might violate the "available" rule above. It's a legit ENG sample with commercial L3 WP tube, but there are only 4-5 of those in existence, so assuming that disqualifies me, I'm going with L3 WP DTNVG + eCOTI on an Ops Core Maritime + G24 with Helstar beacon, Mohawk counterweight, ComTac IV's, PrincetonTec light.
For related bug-out accouterments, I'd run either a Marine ILBE with sleep system or an Eberlestock V90 Battleship ruck/backpack with 3L bladder and extended IFAK/Med Kit augmented with various antibiotics, potassium iodide, etc. Crye JPC plate carrier with Hesco 4800 Level IV plates, Mayflower RC chest rig, basic load-out. I'd probably run a Yaesu or Icom multi-band radio and PTT for ComTac.
Primary gun would be a suppressed KAC SR-15, Elcan SpecterDR 1/4x, CRATOS clip-on, RAID-x IR, SF M600 DF light. Secondary would be my trusty Agency G19/RMR/X400V.
I figure that whole kit is about 90-120 pounds depending upon ammo and supplies/food.
If it's SHTF because of an EMP, well... things just got lighter!