As much as I've a liked this idea since Zubrin proposed it, it's probably the most energy-intensive way of attempting to colonise the solar system. Materials would be incredibly difficult to transport to Venus unless most of it comes from a lower gravity environment like the asteroid belt. In other words, there's a logistical complexity which has always made the proposal so disappointing, and quite depressingly so. Those Earth-like conditions 50km above the planet's surface seem almost perfect.
The Moon has an near-term ROI, which means it'll see a lot more business over the next century. What Billionaire in their right mind wouldn't want to be a trillionaire? Id say, maybe, half a dozen mining outposts by 2100? It's possible.
The one place I've eyed up over the years is Titan. Abundant Hydrocarbons, mountains of frozen water, Nitrogen in the atmosphere for fertiliser, surface pressure only slightly greater than Earth at sea level. Two significant issues would be the surface temp of 93K and gravity not much different to the Moon. But to be able to walk on the surface of another world without a pressure suit, wouldn't that be a thing? *thermal protection advised*