I know–taken from the vantage point of Christian interpretation, it might seem a dumb question. So bear with me. Here is 2 Samuel 7:11b-16:
“Moreover the LORD declares to you that the LORD will make you a house. When your days are fulfilled and you lie down with your ancestors, I will raise up your offspring after you, who shall come forth from your body, and I will establish his kingdom. He shall build a house for my name, and I will establish the throne of his kingdom forever. I will be a father to him, and he shall be a son to me. When he commits iniquity, I will punish him with a rod such as mortals use, with blows inflicted by human beings.
This could all so easily be about Jesus, until you get to: “When he commits iniquity, I will punish him with a rod such as mortals use, with blows inflicted by human beings.”
Even if you want to say God somehow punished Jesus on the cross (uhh…), Christians don’t (generally) believe Jesus committed any iniquity.
So that part, at least, has to be about David’s literal next-of-kin descendant, Solomon.
Verses 15 and 16 go on:
But I will not take my steadfast love from him, as I took it from Saul, whom I put away from before you. Your house and your kingdom shall be made sure forever before me; your throne shall be established forever.
There are at least Messianic undertones to this whole passage, though. Surely God had more than just Solomon in mind when he spoke these words. He is, after all, promising a throne to David forever. Two other things:
1. The lectionary reading stops after v. 14a (!), so you don’t get the stuff about punishment. Is this to intentionally make it read more like it’s about Jesus?
2. The parallel passage in 1 Chronicles 17 also omits the iniquity part… does this mean the Chronicler was taking it to be a Messianic promise (only), too?
What say you, O readers? I’m still mulling this one over.