Well, yes it does, because your belief that chapter 7 is talking about a NT believer is what you have been using as evidence that those who walk according to the flesh, who have their minds set on the flesh in chapter 8, who are hostile to God are believers. If chapter 7 is not speaking of believers, then neither is chapter 8 when it speaks of those who walk according to the flesh.Honestly, this issue really doesn't make much of a difference in seeing that this passage is focused on the two natures and not on "total inability."
In fact, if chapter 7 is speaking of the unbeliever, then the contrast in chapter 8 is between believer and unbelievers: Believers are those who walk according to the Spirit, who have the Sprit of God dwelling with them; unbelievers are those who don't have the Spirit, who remain under bondage to sin, and so continue to live according to the flesh.
And the unbelievers are the ones who have have minds that are hostile to God (meaning they hate God), and the reason for that hatred is that their minds cannot subject themselves to God's demands upon them, and they cannot please God.
Or to state it the other way around, men in their natural condition, without the inner work of the Holy Spirit, cannot subject themselves to God's law, and they cannot please God, and as a result of this they hate God. Their hatred of God (which would cause them to be God and gospel rejectors) results from something they are powerless to change. So they are in a big pickle, because they are indeed unable to respond positively to the gospel message.
It is in Ephesians 2 that we find the solution to this big pickle men find themselves in. It is the inner quickening work of the Holy Spirit, which comes while we we are dead in sin, while we are sold under bondage to sin, while we are walking according to the flesh, while we are unable to submit to God's laws, unable to please Him, while we hate Him, while we are by nature objects of His wrath, while we are in a condition from which it is impossible to respond positively to God.