Yes, the creation of a professional summer league has been proposed: http://teamhandballnews.com/news.php?item.528
Additionally, the French Handball League is scheduled to bring the “Final Four” of their league’s cup tournament to Miami in 2009. This attempted outreach is similar in many ways to the NBA and the NFL‘s exporting of matches to Europe: http://teamhandballnews.com/news.php?item.529