We have plenty of metallic materials that could stand the heat of Venus's atmosphere, including copper, nickel, cobalt, iron, titanium, tungsten, and chromium, to name but a few (here's a list of elemental melting points), as well as a large number of alloys including carbon steel and stainless steel. Even the sulfuric acid isn't a huge problem with some of these metals (tungsten is entirely inert to the stuff), and some alloys perform even better at this. It appears that the standard material for working with sulfuric acid here on Earth is carbon steel, even in extremely high temperature ranges. (From this report--an analysis of the various metals currently used in sulfuric acid manufacturing furnaces)
So the metallic components of a Venus-bound spacecraft really aren't the problem. The limiting factor seems to be the electronics. Even though silicon wont melt at those temperatures, heating up a circuit board to 457°C together with sulfuric acid has repercussions, and will quickly ruin most of the circuitry on the craft. With our current slate of electronics-worthy materials, we are not going to be able to make a circuit board that could survive on Venus.
However, we can insulate the important electronics, and much research has been done on that front since the last Venus mission. In particular, it appears that aerogel materials are being looked at to insulate the circuitry from the combined force of the heat and the sulfuric acid.
From what I can tell, this technology is probably advanced enough to make a craft that, in a perfect scenario, could function fine on Venus for a fairly long time, maybe even as long as the Mars rovers. But there are always kinks to be worked out, and I doubt that we could reasonably expect anything as long-lasting as the Mars rovers for a while.