LOTRO Players announced the news on Twitter: "LotRO is getting a new class later in the year. [Executive Producer] Aaron Campbell just said it on livestream. No other info is known at this time."
Speculation is wide open, although Campbell did drop a few clues according to livestream listeners: "He did state that he had a conversation with Tolkien Enterprises and it's within the lore of the trilogy. He said that it was mentioned in the books several times."