It could - and most probably would - rise up again, eventually. Rising up from the half-buried wreckage of modern civilization is easier than building it from scratch.

Not necessarily. To be blunt, we've basically exhausted practically all the useful non-renewal natural resources (ores, etc.) that a civilization could access with 1200s-level technology. They'd have to mine our ruins for metals and such - and much of it is going to be locked up in forms that are completely useless.

Of course it's nowhere near the guaranteed -- notice, for example, that I excluded all other catastrophic risks from consideration in that scenario, such as crazy wars for scraps, only looking at the effects of shortage of resources stopping much of the industry, because of dependencies that weren't ensured.