I'm not aware of any scholar who would argue this. The main difficulty with such a proposal is that the letters in many cases presume knowledge of the situations being written about, which someone writing for posterity would presumably include.

For instance, it seems clear that in places Paul is responding to queries sent to him by the church to which he is writing, but it is not always clear what has been asked. In some cases, such as 1 Cor 6:12-20, it is not even clear whether what Paul is writing is what he wants the Corinthians to do, or their own words quoted back at them, to be corrected.

Having said this, there's at least one hint that they were being still circulated and read later on: 2 Peter (which most would date one of the later books of the NT canon) in 3:16 makes reference to Paul's letters and the other Scriptures, so perhaps by this point there was a feeling that the earlier writings were being preserved and should be.

Another issue which may be significant, but which is debated, is to what extent Paul expected Jesus to return imminently (within the lives of his readers). This would obviously mean there was no posterity for his letters to be read in!