There is nothing in the New Testament about "90% of Jews dying" nor of "the remainder converting to Christianity". Yet, the idea is not without validity, and I believe you are right to ask for a Scriptural reference that underpins the basic concept. In Luke 21:20-24, the Great Jew told his disciples, "Now, when you see Jerusalem surrounded by military camps, then understand that it is about to be made unfit for human habitation. "At that time, let those who are in Judea escape to the mountains; let those who are inside Jerusalem get out; and let those in the countries not go into Jerusalem." I won't quote the whole passage, but you can read it yourself or ask a further question.
UN chief condemns Palestinian toddler killing, urges calm (Reuters)
from the article: Syria: Israeli nuclear weapons are sparking Mideast arms race