Chameleon power armor is over the top and strikes me as gratuitous power gaming.
That said I would not mind a stealth suit added to the game, something to make your stealth skills a little better. Think like thermoptic camo. There are quite a few sound scientific principles which could be extended in a sci-fi setting which would allow for the creation of a stealth suit, but attaching them to tank armor just aren't feasible.
Altered reality, photoelectric "smart cells," and "light scattering materials" could all be used to create virtual invisibility. Currently none of these are viable options for the purposes of creating militarily useful invisibility, but this is not to say that the principles could not be used to establish such in a sci-fi game like Fallout. I would certainly like to see a thermally controlled light sensitive suit which molds its color scheme or exposes different materials (in the case of light scattering materials).
On a different note I would propose some changes to the armor system along with the addition of new armors and armor types.
I would consolidate the damage system for the purpose of maintaining internal consistency. As a tenuous list the damage types would be:
Normal:
Poison: (Gas weapons would do poison damage)
Explode:
Fire:
Electrical:
Laser:
Plasma:
Radiation:
I can certainly see why some people might wish to differentiate laceration from blunt trauma, and thus I state that the above is a tenuous list.
The reason why I would add poison and radiation to the list is exactly because power armor (and the environmental armor from BOS, which if a RAD suit made an appearance in F3 would be very similar) added poison and radiation resistance, and I would make the base resistance to each type of damage based on endurance, and not just poison and radiation.
I would like to think that someone with more endurance is going to be able to take a punch better. I don't just mean more; I mean even if you scaled the strength of the punches to account for differences in HP that the person with more endurance should still be able to take more.
So things which are conceivably resistable like normal and poison have a 1.5 or 2 times endurance value in base resistance. Things which are hard to resist like electrical and fire get 1% per point of endurance. And things which aren't really resistable like laser, plasma, or explode get 1/2 endurance value in resistance.
This would in my mind also put endurance on par with agility (which I am pretty sure is considered to be the best stat in Fallout), or at the very least make people think twice before dropping their stat down to 4 and thinking they will be good.
As far as armors go I definitely think more simplistic armors would be good, but I am thinking more in the mid range. Padded clothing is already your leather jacket/leather armor. I'm thinking more along the lines of "Firefighter suit" which would give good fire, decent electrical, and some radiation resistance (plastic does a nice job of stopping alpha, beta, and neutron emissions). Or a hazmat suit (like what biochemical or utility hazmat teams use) which would give good poison, decent electrical, and some radiation resistance. The addition of a RAD suit would definitely be a nice touch. I would like the addition of a riot suit or kevlar suit of some kind; not as good as combat armor, but definitely better than leather armor and still affording good AC. I like the idea of a space suit, and it wouldn't be hard to justify if the game extended into houston where the remains of the Johnson Space Center could be found. The space suit would afford good all around protection, but would probably decrease your action points/agility to suggest its bulkiness without the motor assists of power armor.
To keep in touch with the games sci-fi roots I would like to see some special military armor that is some where between power armor and combat armor (brotherhood combat armor was a joke as MkII combat armor was better or equivalent in most ways). Tesla armor was a nice touch, but I think the field could use more types.
I do agree that the futuristic/prototype armors should be rare, but I would like to see more variety.
It is variety that really trips my trigger, because I like options. That's how I could enjoy F:BOS. I didn't enjoy it as an RPG; as far as RPG's go its rather sucktastic. I enjoyed it as a battle simulation game, since it afforded me more tactical flexibility than normal fallout due to its inclusion of more weapons and the option of changing stances, and including more tactical flexibility into a main fallout game would not take up inordinate amounts of file space, and could only add to the experience.