Arguments about the decline of poetry's cultural importance are not new. In American letters they date back to the nineteenth century. But the modern debate might be said to have begun in 1934 when Edmund Wilson published the first version of his controversial essay "Is Verse a Dying Technique?" Surveying literary history, Wilson noted that verse's role had grown increasingly narrow since the eighteenth century. In particular, Romanticism's emphasis on intensity made poetry seem so "fleeting and quintessential" that eventually it dwindled into a mainly lyric medium.
poetry's cultural decline has been known for awhile and it seems that it has been known that even earlier forms of poetry would die out. The paragraph states that poetry dwindled due to the pressure put on it by romanticism and it became a majority of lyrical medium.