ramban on avrohom and pharaoh

In Bereishis 12:10-20 the torah tells us how Abraham went down to egypt because of a famine. The Torah tells us that Abraham lied to Pharaoh about his wife Sarah,telling him that she was his sister, because he was afraid he would be killed (since pharaoh would want Sarah for himself). The story continues that Pharaoh tries to take Sarah and as a result he and his family are struck by plagues until he finally returns Sarah to Abraham and then sends them off with great wealth.

The Ramban comments that Abraham was punished for lying and as a result his descendents would be slaves to the same Egyptians. He says that this story falls under the category of "the deeds of the fathers are a sign of what will happen to the children". The story also hintsaccording to the Ramban, how in the end the jewish people will be chased out of egypt with great wealth.

I would like to humbly add to the Rambans idea by pointing out the similarity of both stories. Abraham went down to Egypt because of a famine so too did Yaakov and his children. Pharaoh only let Sarah go when he and his family were personally hit with plagues. So too, the future Pharaoh would only let the Jews leave when he and his family were personally struck by the plague(killing of the first born). Its also interesting the language by Abraham where it says that the Egyptians praised her(Sarah) to Pharaoh. Before the Jews left Egypt(Exodus 11:3) it says "G-D disposed the Egyptians favorably toward the people".

I wonder if there is any connection later on in Bereishis 21:21 where after Abraham sends Hagar and Ishmael away, Hagar takes a wife for her son from the land of Egypt. Is the Torah telling us that Ishmael would blend into Egypt and not be persecuted because he was not considered the heir of Abraham and would therefore be spared the punishment of slavery/exodus as a result of his fathers actions. On the other hand, perhaps Abraham recieved the punishment of being forced to send his oldest son away into exile thus causing his mother to marry him off to an Egyptian woman-the antithesis of Abrahams beliefs and philosophy of one G-D, as a result of his dishonesty with Pharaoh.