During the famine Yosef collected all the money in both Egypt and Canaan. In the following year Yosef acquired ownership of all the land in Egypt (except the priests') for Paro, but it says nothing about land beyond Egypt. If those in Canaan had already spent all their money and the famine continued for several more years, what did they do? Did they all leave (or die)? Did they find some other way to eat and, if so, what was it?
Rashi on v19 says:
and give [us] seed-: [with which] to sow the soil. Although Joseph said,“and [for] another five years there will be neither plowing nor harvest” (Gen. 45:6), as soon as Jacob came to Egypt, blessing came with his arrival, and they started to sow, and the famine ended. So we learned in the Tosefta of Sotah (10:1-3).
But that doesn't seem like it helps Canaan -- Yaakov left there, after all, so if the blessing is location-dependent things would have gotten even worse in Canaan. And even if Yaakov's arrival ended the famine everywhere, it apparently wasn't immediate because the people sold their land after his arrival -- so Canaan is presumably still affected too.
