Jamieson, Fausset and Brown on 1 Chronicles 17:14

14. I will settle him in my house--over My people Israel.

and in my kingdom for ever--God here asserts His right of supreme sovereignty in Israel. David and Solomon, with their successors, were only the vicegerents whom He nominated, or, in His providence, permitted.

his throne shall be established for evermore--The posterity of David inherited the throne in a long succession--but not always. In such a connection as this, the phrase "for evermore" is employed in a restricted sense (see on La 3:31). We naturally expect the prophet to revert to David before concluding, after having spoken (1Ch 17:12) of the building of Solomon's temple. The promise that his house should be blessed was intended as a compensation for the disappointment of his wish to build the temple, and hence this assurance is appropriately repeated at the conclusion of the prophet's address [Bertheau].