I like Acbagel cut better for it feels more like Vader is actually trying to catch Kenobi (force extinguishing the fire a second time after an explosion that makes the fire bigger and harder to force jump across). Also, Vader saying nothing feels more in character to me than talking to no one. Vader is not a big talker.
I see your point, but I won’t do that. I think it diminishes Vader’s abilities if he is unable to get Kenobi in this situation. He extinguished the flames ten seconds prior to the second fire. In my eyes, if Vader actually really want to get him in this scene, he is - as far as I’m concerned - highly incompetent, which I don’t want him to be. He could extinguish the fires. He could force push or grab the droid. He could’ve summoned the three Inquisitors through the force to immediately hunt down Obi-Wan and Tala in their obvious route of escape through the canyon’s, listening and sensing for Obi-Wan’s screams in agony and presence. He could do a high leap over the flames. He could even throw over some of his own Stormtroopers if necessary. And on and on it goes.
Perhaps the line is not the best fit, but it does clarify - imo - that he is disappointed and will proceed his hunt when Kenobi has regained some of his confidence. The kill would not be a satisfactory one - as of yet.