Why get overly scifi. Think about minor stuff like a chip that moniters a persons health state and can alert authorities to tramatic injury or illness.
implants that can release nutrients into the body for soldiers/hikers so they are less likely to suffer various ailments such as dehydration, or nutritional deficiencies. hell theyre already sticking GPS in folks.

Hmm, a nutrient pack seems like a really cool thing, and the great thing about it is that it wouldn't necessarily need to be bulky to be effective. If it used a system similar to a nicotine patch to get it into the blood, then you could get the most important trace minerals easily, or even tailor it specifically to your needs(example, you're going sailing for a few months and are planning on catching most of your food, get a few Vitamin C canisters instead of a Vitamin C, iron, zinc, nickel loadout or something.)

There was some talk a few years ago about replacing a pilots survival rations with something similiar. a high density energy bar about the size of a snickers that could be divided into 6 pieces, each piece having enough carbs, fat and protein to last for a day and about 10K calories. the problem still lay hydration. Survival water still takes up a bit of space on the survival vest and doesnt really count for much...basically a days worth although with various supplements to make it stretch a bit better.

a better choice would be something that when ingested destroyed appetite as digesting food uses up water that could otherwise be spent not dying. We certainly dont eat prior to patrol due to the same reason. (that and because all the good MRE's are gone by now...how i miss you cheese tortellini)

Hmm, how small can they make the wastewater recycling units? If they make them small enough, and make them draw only a little bit of power, I could see fighter pilots wearing waterproof flightsuits that filtered their waste fluids, powered by some small solar cells on the flightsuit. I bet they can make one smaller than a parachute or radio.

Night vision can be attained genetically and so can binocular vision and even a heads up display like I said before. If the eye furthermore regenerates then durability isn't much of a problem, not that it would be much different with a mechanical eye, shrapnel goes through both.

I'm quite badly visually impared (10% vision in my good eye), so... yes =p. It's quite possible I think, only a matter of time. Affording it however...