Consider, if you will, two factors in anticipating the next SV: timeline and output. The Diablo SV arrived in 1995 (five years after the Diablo was first introduced) and packed 510 horsepower (compared to the standard Diablo's 492, though there was a more powerful Diablo SE30 Jota with nearly 600 horsepower before the model was phased out). The Murciélago SV, meanwhile, debuted as the most powerful version some eight years after the original with 661 horsepower to the first model's 572.
Apply the same logic to an eventual Aventador SV and we're looking at nearly 800 horsepower, if and when it arrives some five to eight years from now (several years after the anticipated roadster comes along). Now that's a mouthful and a half, and though there's not much weight to be trimmed off the new Aventador's carbon-fiber monocoque chassis (compared to the Murcielago's steel frame), who knows what kind of new materials might be developed by the time the Super Veloce comes rumbling along.
Until then we'll just have to make do with the current version and its 691 horsepower, 2.9-second sprint to 60 and 217-mph top speed, and try not to get ahead of ourselves. Which is just as well, because with those kinds of numbers, not much else will be, either.