Valve is replacing its current Big Picture mode with the user interface from the upcoming Steam Deck console.
In a post on Steam, Valve moderator Austinp_valve said that at some point in the future, Big Picture mode – used for navigating Steam with a controller – will be replaced by the UI for the Steam Deck hardware. There's no indication when this will be happening, however.
"Yes, we are replacing Big Picture with the new UI from Deck," Austinp_valve wrote.
"We don't have an ETA to share yet though."
Valve unveiled Steam Deck has week and has seemingly drawn a lot of attention given that pre-orders for hardware were third highest-selling item on Steam last week. The hardware is set to launch in December.
The company has also said that it has done a lot of reliability testing for the console, so hopefully we won't see the stick drift issues that Xbox and Nintendo's hardware have experienced.
Big Picture mode was rolled out in beta back in 2012 and was intended primarily to be used in Valve's Steam Machine initiative. The UI hasn't been updated since 2015, so is long overdue an update.