Moving toward modern times, Pierce reveals how both the crisis of the exile and then the coming of the Messiah (Jesus Christ) with the New Covenant promised in Jeremiah reveal a difference between secular and spiritual repossessions of the land. He states that Israel's inclusion in the New Covenant is still a conditional promise based on obedience. In discussing Romans 11, he posits that Paul has more of a hope or expectation that God will offer another opportunity for Israel to enter into the new covenant if they do not continue in their unbelief as opposed to a prophetic word about its guarantee. In support of this claim, Pierce makes some limited observations between the times of the Messiah's offer and modern Israel in which any reclamation of the land was secular, not spiritual (the exiles returned without true repentance, the Hasmonian political dynasty, etc.) and as a result the land was either quickly lost or was dominated by foreign rulers. Furthermore, not even the latest return led by modern Zionists led to any prophetic words regarding God's intend for Israel's future.
A modern application of seeing the conditional nature of these covenants would be to stop the unconditional covenant mentality which has led to the “biblical guarantee” of Israel's future as a nation state and the subsequent blind support for Israel's politics. This also cautions that predictions about Israel beyond 1948 should be avoided, for ultimately we don't know what God's final plan is for Israel.
Personal Observations – Pierce's works certainly could take the wind out of the sails for eschatological predictions regarding Israel. God's promise to Israel in Romans 11 seems to be limited to an offer of restoration, as opposed to the promise of restoration itself. If so, the nation we currently know as Israel could fall away again with hopes to be reclaimed, or not, and God's name would not be diminished. In the end, whether we opt for a Dispensational or Covenant interpretation, we should all agree with Pierce that “It seems best to join the apostle in his prayer for their [the Jews] salvation (10:1), but to base future hope on the established pattern of God's grace, offered and reoffered to Israel in special ways despite their failure, rather than on the notion of an unconditional covenant” (Pierce, 38).
Pierce's Article in Journal of the Evangelical Theological Societyhttp://www.etsjets.org/files/JETS-PDFs/37/37-1/JETS_37-1_027-038_Pierce.pdf