Two merchandise stores in the Magic Kingdom will be closing tomorrow (January 4, 2014).
Seven Dwarfs' Mine, located in Fantasyland and Heritage House, located in Liberty Square will close their doors for the final time at the the end of today. Disney have not announced why the shops are to be closed. We can speculate however, and presume that Seven Dwarf's Mine is likely closing for a rebranding to avoid confusion with the Seven Dwarf's Mine Train Coaster due to open soon.
There's no known reason why Heritage House should close however, and it's one of the few locations in the park to offer American History themed merchandise.
It is possible that the shop could become another MyMagic+ kiosk, providing a central FastPass+ location and a helpdesk for guests.