I’m reading over Craig Keener’s Galatians (NCBC; Cambridge: CUP, 2018), trademark Keener, readable and suffused with historical descriptions, lots of great remarks on the background and theological significance of the letter.
Rather liked Keener’s take on the “Israel of God” in Gal 6:16:
Paul normally uses “Israel” to mean the Jewish people, but in at least one instance qualifies this label (Rom 9:6), and once he speaks of “Israel according to the flesh” (1 Cor 10:18). Calling anyone else Israel is not, then, Paul’s usual langauge. It is, however, a fitting climax in this polemical letter. Paul is not, however, adopting the later Christian supersessionist practice of a group claiming to replace ethnic Israel. Rather, he is thinking of believing gentile branches grafted into the single eschatological people of God (Rom 11:17, 24); these are the eschatological converts promised by the prophets (e.g., Isa 56:3-8; Zech 2:11). Granted, for Paul, unbelieving branches, whether Jewish (Rom 11:17, 19) or gentile (11:21-22), are broken off. But Paul also affirmed that in the end time Israel as a people would also convert to faith in the Messiah, convincing by the obedience of so many gentiles to their God (11:25-26; cf. 11:11, 14). Far from discarding historic Israel, Paul is seeking to anchor his gentile converts clearly in connection with it.You can read this commentary by Keener now, it is 332 pages; but if you wait until November, you will be able to get Keener’s bigger and more thorough Galatians commentary published by Baker which is 736 pages.