“Nevertheless, I myself will remember.” There is now a distinct shift in the emphasis and tone of the text. God now promises the restoration of Israel. Whereas Israel and Judah had sinned egregiously and deserved (and received) punishment, now God promises He will remember His earlier covenant with Israel (the “Old Covenant”) and so will establish a new covenant, an everlasting covenant, with Israel.
In the Old Covenant, God promised that Israel would be God’s own possession, a kingdom of priests and a holy nation (Exod. 19:5-6). Although Israel failed to keep their part of the covenant, God remembered His original intention and planned to put a new covenant in place that would be an everlasting covenant. Salvation is always individual and personal, never corporate. No one is given everlasting life just because they are part of a group, even if that group is the Jews, God’s chosen people. From the scope of Scripture, we learn that it is the people who obey God and are saved that get to be part of the New Covenant and live forever on a restored earth.
“an everlasting covenant.” This refers to the New Covenant that God will establish with Israel.
“in the days of your youth.” The covenant God made with Israel in the days of her youth was the “Old Covenant,” made at Sinai just after Israel had left Egypt and as it was forming as a nation, not just related tribes (Exod. 24:1-8).