Super late reply, maybe not relevant anymore:Has anyone seen new laptops/tablets with video input? Is it possible to replace the monitor for portable setup in this way?
I don't think I have EVER seen any ordinary, general purpose laptops or tablets with a video input. The only exception I have seen is the many thousand dollar Wacom MobileStudio tablet computers are able to be connected to a computer and used as if it were a Cintiq with an adapter they sell, and along with that the iPad pro can be used as a drawing tablet for an Apple computer. probably not what you're looking for though.
If you're running windows, though, you CAN mirror or extend your desktop to the monitor(s) on another machine on the network also running windows, but that's only as good as your network.
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So a device I've had my eye on is the Taihe Gemini. That's got ALL the ports so should actually be able to connect to basically anything (only super recently have these other options for non USB-C monitors popped up), and is a touchscreen. I haven't seen any reviews, though. Does anyone here know anything about it?