I wouldn't be that stunned if Microsoft introduces an XBox branded portable PC.
Steam Deck is clearly not a one off product, now you can see other PC manufacturers getting in on the act like ASUS with the ROG Ally, and this unlike the Steam Deck is even available at normal retail like Best Buy.
It wouldn't really take a whole lot for Microsoft to make something like that, they could get the same or better APU from AMD and they already make Surface tablets. It wouldn't even be some huge hardware investment, they'd just be using a standard AMD APU.
The big knock on Sony/MS having to release a portable was it would split their dev resources, but with the way MS' ecosystem is set up, a ROG or Steam Deck device from XBox would automatically basically run all of MS' games anyway because they are all designed to work on a PC so that whole problem of "yeah but if you make a device like this it means you can't support your home console as much because dev resources are split!" kinda goes out the window.
So I wouldn't necessarily say Nintendo is guaranteed to be the only one of the big 3 to ever have a hybrid device forever and ever. That could change in next couple of years.
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