My understanding is that the new version will have extendable sky limits? If that is the case, I'm looking forward to seeing 3D visualisations of future mega-towers. I'd like to see a tower that pumps magma right up through the center and out the top, cascading downwards into a surrounding moat!
The best part will be throwing a goblin off the top, one 100 z-levels above sea level, and as he falls, passing through the cloud layer, getting showered with a light drizzle that washes the bloodstains from his face and broken hands, seeing a couple of red cardinals and a skeletal giant eagle that barely has enough time to screech as he flashes past, he has time to wonder about the meaning of his life, and whether he should have better spent it as a priest, waiting out the inevitable decline of his civilization to the dwarves.
Eventually he'll fall close to the ground, and the above-ground magma foundries of the dwarves will send up a smoke that obscures vision, but he is able to see that his fall is directed near to a pit, and just as he falls by the rim of the pit he passes by mere inches a dwarven toddler, scaring it witless and scarring it for life.
Down into the underground z-levels the goblin plunges, until the sun above is no more than a speck of light. At first he falls through a natural cavern whose walls sparkle with as yet unmined out minerals, then through a glass shaft that runs deep into the earth, through solid stone, though occasionally opening up to a lightless void where shadowy figures snarl in the distance.
Eventually, there is no more light, and he loses track of time, wandering if his fall will never end. Abruptly he hits something large, scaly, and bounces off, stunned both by the landing and by the fact that he didn't die immediately in a shower of gore. Then, something rips off his arms, and as the monster starts to dismember him, he wishes that he had hit the solid bedrock instead.