There are already a number of identical posts
General Posts:
http://forums.androidcentral.com/mo...hing-moto-could-add-make-you-buy-moto-x2.html
http://forums.androidcentral.com/mo...-change-moto-x2-assuming-there-would-one.html
Specific to Screen Size:
http://forums.androidcentral.com/moto-x2/377477-moto-x2-4-7-vs-5-screen.html
Camera:
http://forums.androidcentral.com/moto-x2/376126-dreaming-better-camera-moto-x2.html
As discussed in the other threads, most here feel the phone needs to stay about the same size. They could fit a 5" screen on the same form factor.
In regards to the camera, more megapixels isn't the answer. Larger sensor, larger pixels and better optics are needed. If they want to get fancy they could maybe add a second sensor with a different f-stop. Duel LED flash and possibly zenon flash as well.
If they move to a SD800 or above, I don't know if they would need "x8" since the newer Snapdragons have the features of the "x8" custom cores built in. Given its release timeline, I would like to see an 805, which should be more power efficient and tuned then the 800 or 801.
Larger battery and, if they move to a larger screen 1080 resolution.
Personally, I would love to have voice print verification, to allow you to use the phone in locked mode in combination with the always listening feature.