I think there are a few dynamics happening in that relationship.  First, I think it's very likely that biblical preaching will increase personal counseling, at least at first.  So many sermons in so many churches stop at some well-worn moralism, and the fact is that the human soul is really good at erecting defenses against that kind of thing.  But in a robust expository preaching ministry, truths are going to be explained and applied in profound ways, and the Holy Spirit is going to work specially through the preaching of the Word.  The result, I think---not surprisingly---will be that people will find themselves convicted of sin and righteousness in new and important ways.  And they're going to want to talk about it, most likely with the guy who was God's instrument for stirring up the "problem" in the first place.  That's good.

In time, I think it's possible that people will learn how to handle the upheaval that happens in their souls without the need for in-depth counseling from the pastor.  They'll understand Scripture better, they'll understand their hearts better, and they'll be able to apply the Scriptures to their lives more readily.  But that doesn't come from moralistic sermons; it comes from a long, deep ministry of preaching the Word.  And the result, put simply, is more mature Christians---which includes being able to counsel oneself.

Another point, though----and a much more important one---is that over time, the entire congregation will learn how to counsel people in sin and difficulty.  So at the beginning of an expository preaching ministry, the pastor who's doing the preaching may be the only guy in the congregation with the resources to be able to get into the details of someone's life and give them good, solid, biblical wisdom.  But keep preaching the Scriptures, and the congregation is going to mature.  They'll get wiser, they'll get more compassionate, they'll understand the gospel and its implications better.  In time, you'll have a whole congregation that is really prepared to do the kind of "body work" that I think is expected of a church.

So instead of everyone thinking they need to talk to the pastor, they'll realize that there's wisdom all over the church:  Their brothers and sisters are able to bring the Scriptures to bear in their most difficult problems.  Eventually, counseling will be taking place all over the church as the members talk with one another, share struggles, and apply Scripture to one another's lives.  Of course, the pastor will always be a go-to guy for personal counseling , but I think the goal of an expository preaching ministry must finally be a church where everyone is growing to maturity in Christ and learning to help others do the same.  Again, though, that kind of maturity doesn't come from nice stories and moral fables.  It comes from faithful exposition of God's Word.