This slide from a presentation by George Whitesides the CEO of Virgin Galactic, plots the log of the top speed of human vehicle by year. For the past couple of centuries, the top speed was increasing steadily, at a Kurzweilian rate. But in the last few decades, the top speed of a human vehicle (a space probe traveling at 14,000 miles per hour) has plateaued. But, notes Whitesides, if we could resume ten fold increases in speed (like we have in computers!) we could reach the speed of light by 2060 (the vertical red line on the right). That would make interstellar travel feasible (and Virgin Galactic very happy!)
Big if. At the recent 100-Year Starship Study conference where Whitesides gave this presentation, many hypothetical methods for reaching ten-fold increases in human speed were proposed. The weaknesses of each idea are very visible. Not every log curve continues; while progress in speed seems certain, the pace is not.
Most of the Kurzweil curves we have experienced are technologies based on information. Those technologies based on energy -- transportation, solar, batteries -- are generally NOT doubling anywhere at the rate of information.
I'm going to bet against light speed in this century. But I hope someone more imaginative and willfully ignorant than I comes along to prove me silly.