e to Phinehas was for an "eternal priesthood," not an eternal high-priesthood, and since the high-priesthood did return to Eleazar's line through Phinehas, the promise was kept (42-43). Additionally, Porter comments that the prophecy is a call to the people in general (335).
In the context of the immediate passage, the prophecy is a good example of God's judgment: sudden, unexpected, and predicted. God gave His law to His priests and His judgment on those who broke it so no one should have been surprised at what happened to Eli and his sons. But in His grace, God gave Eli two more chances in addition to His word: this prophecy from the unknown prophet and the one given to Samuel himself in chapter 3. Ironically, both times Eli merely acknowledged the word of the Lord without doing anything about it, trampling the grace of this warning.
Keil and Delitzsch note that in 2:27, the author does not use the interrogative but the emphatic, as Jeremiah did in 31:20. The style is therefore a rhetorical question: he isn't asking Eli but telling him. Although God chose
...