Thought for Shemot: Paroh's Plan was Destroy the Jewish People through Intermarriage

Paroh's plan doesn't really make any sense: why kill the only the Jewish boys, and not every Jewish baby? Ohr Hachayyim (on Shemot 1:16) makes a startling suggestion: he was hoping to enslave the Jews through intermarriage:

והנה עצה חכמה יעץ פרעה בדבר זה, לבל יוכלו עלות מהארץ, והוא כי באמצעות שיהרגו כל זכר ויתרבו הנשים והן האשה טב למיתב טנדו ויתחברו נשי ישראל עם המצריים ויתחתנו בהם, ומעתה אין מציאות לעלות מן הארץ כשיהיו לעם אחד. גם יפגימו הנפשות הקדושות בערבוב הנפשות הטמאות ויהיו שם עד עולם ב''מ. And behold, Paroh offered sage advice in this matter which would prevent the Jews from leaving the land by killing all the males and increasing the [percentage] of females. Since it is known that "it is better for a woman to be married [than remain alone]", the women of Israel would associate with the Egyptians and marry them. From that point on, there is no possibility for them to leave the land as they would be one nation. Moreover, their holy souls would be blemished through the intermingling with the impure souls [of the Egyptians], and they would forever remain as a minority [in Egypt].