Copenhagen is hosting LEGO World today, and on display in the shop at the event is a series of LEGO Night Mode sets. Each one is an official light kit for a specific set, with Brickset sharing images of the various boxes.
According to the LEGO collecting website, they are just empty boxes on display but with prices, suggesting that these are to to gauge fan reaction rather than available for purchase.
Light Kits are on display for 71043 Hogwarts Castle, 10260 Downtown Diner, 21318 Tree House, 10265 Ford Mustang and 41374 Andrea’s Pool Party. Brickset reports the Hogwarts kit as priced at 1449DKK (approx £160) and the Tree House kit as priced at 649DKK (approx £70).
Small companies have produced lights for LEGO models for years. It used to be that lights would be sold to use as fans desired, but more recently, companies such as Elegant Bricks have been creating lighting kits for specific LEGO models. It seems that now the LEGO Group itself has decided to step into that very market.