Elected as in chose a path of life between Jacob and Esau.
This does NOT imply salvation.
One MIGHT be elected for many things.
ELECTION is NOT EQUAL to Salvation!
God ELECTED Israel as nation! Are all in Israel to be saved?
And the passage goes on to state that it does not depend of man's desire or effort, but on God's mercy.(v.16). Not just "Israel's" desire or effort, but "man's" in general. To further the point, Paul says God hardens or has mercy on whom He wills.
No, not all Israel will be saved; only those God destines for salvation and gifts with faith.