Not happening, and probably for good reasons. The Surface Pro have their niche, even at 900g lately it's still not a populated niche. There are laptops under 1kg, but very rare and expensive if you want anything vaguely usable. A 16" device is of course considerably larger (of course, this is why you want it) and heavier, would cross the 1kg mark and surely not stop close, I bet it'll be closer to 1500g. That's already around dirt cheap 15.6" laptop, and we didn't even start to consider the keyboard (still talking weight more on pricing below).

Pricing of course would be a nightmare too, proportional to the weight I guess, surely well over 1000 for the entry level, more likely closer to 1500. The keyboard too would be way more expensive (don't believe me look at Samsung and Apple for the same line of tablets and larger sizes). And we're talking about the regular flex tablet (or anything similar) which is actually nothing out of the ordinary, just a bluetooth+wired keyboard for which there are many out-of-the-box controllers plus firmware . I bet we're talking BOM of a few dollars, if not even under $1, but more importantly there's not much to R&D for that. Still, even with a regular flex&floppy keyboard we're starting these devices (including the keyboard) at $2000 EASILY. Want to add something REALLY special, with a stiff hinge, maybe electro-mechanic locking and so on? That's another $500 as a baseline, but probably sky's the limit.

+1 to all of the above. It's not technically impossible but very unlikely to happen.

Small screen sizes are one element to get long battery life; if you make everything larger, you'll also need a larger battery => more weight, higher costs. Larger size and more weight makes a device less portable and also designing the kickstand more challenging. The kickstand will also require more tabletop real estate to stand firmly.

If mobility isn't a priority but a larger screen is, there already are those stationary things called All-in-One-PCs - which should come with Snapdragon in 2025. HP already has an Intel powered one with a battery (Envy Move 24") => you don't have to use it near a power outlet all the time. And it costs way less than a large Surface Pro ever would...