If you can take Mario Kart and Breath of the Wild on the train, then why not Overwatch?
For the last few months, Chase Cobb has been working on a prototype project: a gaming PC that was "ultra portable". Called Project Scout, it's a portable PC with a i3-6100U CPU (with a HD 520 onboard GPU) and 8GB of RAM into a tiny unit with a 7-inch 1280x800 panel. There's a 250GB SSD in there for storage, along with Bluetooth support and dual band AC Wi-Fi.
The prototype unit doesn't have a battery or a touchscreen, and Cobb says in the video that the hardware isn't the final package yet. That's important, because you can see in the video that it doesn't run Overwatch at a flat 60fps, although games like Psychonauts and Guacamelee look playable enough. The device is also capable of acting as a client for Steam's streaming service (if you wanted to offload the grunt work from your main gaming PC).
He notes that it seems like a perfect device for Nvidia's new Max-Q engineering design, and it'd be fascinating to see what could be done with AMD's Ryzen-based APUs when they become commercially available later this year. Cobb noted in the YouTube comments that a Kickstarter campaign could be an option down the road, although it's very early days and with the existing hardware it would still cost more than a Switch or a regular console.
But let's run a little thought experiment for a second. If someone came to you and said here's a portable, Switch-esque gaming PC that would run basically all indie games and Overwatch at a flat 60fps on a small-ish screen at 720p, how much would you be prepared to pay?