WDWMagic.com user Rteetz is reporting that internal communication on the Cast Member Hub states that guests will soon be able to access Main Street U.S.A. prior to official park opening. Additionally, a new Magic Kingdom welcome show will debut on January 9th.
The current show runs at the top of the Walt Disney World Railroad Station in Main Street U.S.A. on the side facing the entry gates. As part of the current show, the welcome song includes the line, "the castle leads the entry way to seven lands and more". This line has been inaccurate since the opening of New Fantasyland due to the former Mickey's Toontown Fair area being absorbed into Fantasyland. The new welcome show will be performed at Cinderella Castle Stage beginning January 9th.
The full report from the Cast Member Hub is as follows:
With more guests arriving early to the Magic Kingdom park, we are enhancing the morning arrival experience by opening Main Street USA earlier than the rest of the park.
Guest will be able to get a head start on their day they as enjoy the early morning charm of Main Street USA with photo opportunities, breakfast options and shopping before the park officially opens.
A new welcome show will debut at Cinderella Castle stage Jan 9th
The Disney Parks Blog confirmed this report as well.