In years past, the Cubs have typically announced a partial list of the players and former players scheduled to appear the the upcoming Convention. So far, there has been no official announcement confirming the appearance of any particular players and no lists have leaked otherwise.
Contact with the Cubs was fruitless, with the response only, "the list of players for 2016 is not yet available unfortunately, but last year it was released a few days before the convention." (Last year, however, the Cubs announced a partial list of attendees and programs on December 19th!)
We will continue to monitor for official announcements and leaked information and will post updates as information becomes available!