I am trying to understand a comment written in the Stone Edition Chuash (page 288) on Bereishit 50:23. On the statement that Yosef was alive to have his great-great grandchildren through Ephraim on his knees, and the sons of Machir, his grandson through Menashe, also on his knees, the commentary reads,
"The point has been made that Machir's sons were contemporaries of Moses (Numbers 26:29), and they were among the fourth generation that God had promised to liberate from Egypt (15:16). When they were children, they had seen Joseph, the greatest of his generation, and they would live to enter Eretz Yisrael."
According to the Jewish Timeline Encyclopedia, Yosef died in 2309, the slavery began in 2332, and the Exodus was in 2448. The slavery was then 116 years long and Machir and his sons were alive for at least 139 years (the youngest, assuming they were born on the day Yosef died) and probably older than that to have been able to spend any appreciable time on Yosef's knees. Ignoring the incredible age to which they lived (minimum 139 years old when even Levi died at 137) how could they enter the land of Israel -- wouldn't they have been condemned to die in the desert as they were older than 20 years old?