Just recently Valve essentially confirmed there would be more Steam Decks in future when it published an official document while readying for the launch of its handheld in new regions.  

In that booklet, Valve said that:

"In the future, Valve will follow up on this product with improvements and iterations to hardware and software, bringing new versions of Steam Deck to market."

Now while speaking to Weekly Famitsu magazine, Steam Deck designer Greg Coomer and developer Pierre-Loup Griffais have spilt more info about the future of the Steam Deck. 

In the interview, which was translated by VGC, Coomer said:

"Unless something major changes, there will be a next generation of Steam Deck products in the future...The theme, size, and shape will change, and it might even become a streaming machine. Development of the Steam Deck will continue."

It seems that the future of Steam Deck is going to be interesting. Valve is apparently focussing on battery life improvements and optimisations first on future models but is also planning on "many other uses besides this handheld device."

The interview also hinted that Valve is working on games as well. "Game development is very important to Valve. I don’t know the exact numbers, but the percentage of employees involved in game development is high. A lot of people are involved..." Coomer said during the chat. 

Hints were dropped at the possibility of future Half-Life and Portal games too, though nothing official. We certainly wouldn't be surprised to see a continuation of Half-Life Alyx. It seems that the future is exciting for Steam fans both in terms of software and hardware.