I don't think there will ever be an ultimate dozer but from a mechanics perspective I can think of some things I'd like to see in the current production units.
I think there needs to be some kind of winching mechanism that works from inside the cab for the belly pans. I don't know how many hundreds of hours I've put in pulling a pan to change a hose and then jacking or stringing come alongs and chains underneath to get the thing back up. And on that vein why isn't there some kind of adapter that I can use on the machine for dragging tracks on with. Something on the blade maybe or can be mounted on the hard nose so I don't have to use another machine and a 150 feet of chain or cable.
I'd like to see equalizer bars with a center pin mechanism that doesn't have to be jacked in and out with a forty ton hollow ram. I'd also like to see a lot more useful life out of the bushings and pins. I do like the cannon style track frames on the big machines. I hate the suspended undercarriages because they add tons of cost and complexity and I haven't yet figured out yet how they make the dozer more productive.
I want to see a hard nose that bolts on. That stupid pin setup they use now is guaranteed to work loose between 5,000 and 10,000 hours. Usually I don't hear that there is problem until the fan catches the guard and tries to stuff it through the radiator cores. The fix requires pulling the front of the machine apart, welding the bores, machining them and installing all new pins and bushings. I never had probems with the old D8 and D9 dozer hard noses coming loose. This issue I feel is one of those engineering for failure things previously mentioned.
I have seen swivel seats in dozers and found that they get broken with about twice the frequency of standard seat suspensions. I would like to see seats designed for really big people. I really like the air suspended seats.
I do like the new electronic diagnostics in the Cat dozers because they tell you what is wrong and I don't necessarily have to buy a $1,000 service manual or hook up to the internet to figure it out. On the other hand I really don't like that I can't make the engine perform to my specifications or that I have to call out a dealer wrench at a $1,000 a day and still don't get the thing running and still have to pay or they shut off my parts supply.
That's all I can think of for now but I'm sure there are better minds out there that can improve on my list.