How much bigger do you think the Switch 2 will be compared to the current models? Will they be able to fit all of this technology into a size similar to the Switch?
Yes. The major constraint in terms of performance is thermals, and if this is on 4N, which it probably is, those thermals would be in the same ballpark as the original Nintendo Switch.
In fact even if it has an 7.81" display, that wouldn't require a larger body than OLED Model. In fact, by no coincidence, it's pretty much the exact limit for a screen to fit on the OLED Model body.
What I'm expecting in terms of formfactor:
A tiny bit thicker (<1mm), a tiny bit wider (<2mm), a screen taking up the vast majority of the front of the device, a wraparound kickstand at the rear, similar sized Joy-Con with taller sticks and rear grips, and more IR motion cameras; one on the rear of the device above where the Nintendo Switch logo is on the original Switch, and one or two on each Joy-Con 2.0.
If they go with a camera on the device, I expect the "lens", the outward facing part, to look like the IR port on a Joy-Con (R), a black window with two lines, like a tiny visor on the back of the console. I wouldn't expect it to be circular and promenant like a tablet camera.