Jay, I take no position whatsoever on whether Gen. 15:16 refers to 1948. I simply say that not every instance of "generation" in the Torah should be construed to be one of the seven "ages." Sometimes the word just means the average interval of time between the birth of parents and the birth of their offspring. And Ex. 34:7, Num. 14:18, Deut. 5:9, are instances of this. The "generation" in these verses is implied from other Hebrew words involving sonship. You won't find in these verses the actual Hebrew word for generation: תּוֹלְדָה
Perhaps if you considered the Hebrew words in Genesis 6:9 where two different Hebrew words have been translated as "generation(s)" to see the differences between them. The first word is best understood to be "This is the Genealogy of Noah," the second word is best understood to have the meaning of a period of time/age.
This is one paraphrase that I have considered to best translate this one verse: -
{This is the genealogy}/{These are the descendant generations}(H:8435) of Noah. Noah was a righteous man, blameless in his {generation}/{age}(H:1755) before the flood; Noah walked with God.
Plese note that I have added the words, "before the flood" to this verse to emphasise the time period where God came to check up on His creation of man.
I trust that this example helps.
Shalom