Actually you can pasteurize at 130 F, it just takes several hours. I do a lot of cooking at temps between 130-145 F, and with sous vide I rarely go about that (the only thing I do higher being dark meat chicken, which tastes undercooked at temps under 148 F).

I appreciate your concerns about heating plastic, but the food you buy (eg Mountain House) has already been heated in plastic. Everyone has to make those decisions for themselves but with modern BPA-free bags designed for cooking I think the risk is minimal, especially when you keep the temps far below boiling. I don't think much will "leach out" of plastic at 135 degrees F.

I'm not sure how you could hope to "calculate" shelf life if you don't sterilize or pasteurize. The latter results in about a 6D reductions in all pathogenic bacteria. The math would indicate that food prepared in that will last for weeks/months, with many variables. Not much may to be sure if you don't heat treat them.

Pretty much all the common bugs that cause food-borne illness (eg. listeria, salmonella) need most of the same things we do in order to thrive. They aren't killed by lack of water but they can't grow/multiply/reproduce without it. That's why drying food preserves it. Of course, salt also inhibits bacteria. Lastly most bacteria need to have a comfy pH level, too. When you think about salting, smoking, pickling, and drying this starts to make sense.

Bacteria basically need the right temperature to survive. Salmonella, for instance, is killed by a few seconds at 165F. However, it's also killed by temps above 130F...but it takes a lot longer. That's the point of sous vide. Holding food at, say, 140F will do the trick by killing the vast majority of bacteria (maybe 5D or 6D) but not all of it. That's why pasteurized milk, though treated to kill most of the bacteria, will still spoil if you leave it on the counter.

Beyond this level we have sterilization. A hospital might use an autoclave for that. Industrial food processors will use giant "pressure cookers" to heat food up to around 245-250 F. At this temperature essentially everything is killed. That's why canned food or aseptic juice boxes or "shelf stable" milk can be stored in the pantry.

I think it depends on what you plan to do with the food. If you want to open the big cans and vacuum seal packages to take on a two week canoe trip I'd feel pretty confident it would work fine with no additional cooking. If you want to build a stash of small meals for TEOTWAWKI it's probably not idea; for long term you would really have to do some real heat treating.