Pietia said:
Bulldozer is not a tank - it does have tracks but not weapons and armor ;-) .
Panama was not the only time airdeployable armor was used - M551 were the first US tanks in the Saudi Arabia during Desert Shield operation. They didn't have to fight, but they were there.
As for the "not inferior" weapons on Sheridan - the 152mm gun and Shilelagh missile were less capable than 105mm gun, at least US Army believed so when they quickly phased out the M60A2 after investing so much money into research...
"Protection based on mission needs" - you're military, you should understand this. Add-on armor has to be flown in just like everything else. If you have limited airlift assets, you fly in the more important things first and luxury items like extra protection later. So it is not that you'd "want less"- you simply cannot have more ATM.
As for vehicles light enough, powerful enough and survivable enough - practically all vehicles tested as possible Sheridan successors were more powerful and survivable than Humvees, and roughly as heavy as Sheridan (counts as light enough, for sure). They were also lighter, more survivable and powerful than the new expensive PoS called Stryker the US Army is so fond of (and they were available 10 years earlier...). Oh and as for the "need for a tracked vehicle, while present, wasn't overriding enough" part - I guess that guys making these decisions haven't seen how the thing called "road" looks like in many countries...
As for "combined arms" and "armor ready to push in to meet them" - three words: "Operation Market-Garden". I guess that US Army expects to always fight with third-world countries with equipment and doctrine three generations behind their own... If at some moment they will have to fight against an equal or almost-equal opponent, you'll see history repeat itself.
Well, I have seen several bulldozers here with the added up-armored upgrading kits and M240 mounts... no American vehicles are allowed outside a FOB or protected area without the up-armoring systems now, including contruction equipment and semi trucks owned b the military.
What I meant by Panama was that it was the only time the US has used airborne armor systems in an airborne capacity. As for the M60 series of MBT, if I recall correctly they were phased out due to a new concept of armor shapes that would help deflect rounds in addition to new armor making technologies, thus requiring a new chassis. I suppose there were a lot of reasons the M60 series was replaced though.
Armor is not a 'luxuary' item by any means. Although we did get caught under prepared with OIF, as soon as armor systems were available they were shipped and installed. When does one need the most armor, during the opening moments of a battle or later after DZs are secured? During the meeting and clearing phases of course.
As for humvees being more survivable than the Sheridan, the thin skinned are not, and that is what is currently being dropped in the US inventory. I have pretty much been overseas since the up armoreds became widely used so I don't know how they drop, but the chassis is already strained under the wieght of armor it wasn't designed for, so who knows what a heavy drop would be like with them. The problem with airborne armor is a matter of space, to fit on the transport aircraft, and weight. Only X amount of tons may be dropped in a heavy drop. I don't remember if Sheridans were heavy dropped, but I do know they were LAPESed from C130s.
The Stryker is not airborne capable. It is too big and too heavy. There have been a lot of experiments and to my knowledge, it hasn't passed anytihng workable yet. It is just a reworking of the LAV system anyway, butnicely done. Most crews do tend to like them although for the money we should have gotten more. As for wheels vs tracks, you should se ewhat an urban road looks like after months of tracked vehicles run over it vs tires. Tires are also easier to replace in the field and require less skilled maintenance. I crew both a M2 and a M1151 so trust me on this

I'll replace a tire over breaking track any day.
And as for OMG, that was over 60 years ago. Doctrine and technology has changed quite a bit since then. While still not an impossible scenario, it is a highly unlikely one. AAmerican airborne troops were used very differently then than they are now. For examples of modern parachute insertions look up Panama, the 173rd in OIF, and 75th Rangers in OEF.