Being able to "see" beyond our normal senses like our eyes is not predicting the future. Luke "stretches out with his feelings", sensing wherethe bolts will come. Spidey sense, basically, or a form of super-human (aka paranormal) reflexes. As I said, this would be akin to Obi Wan "knowing" that he can make the jump to the droid. This is much different from the complex, long-term prediction Obi Wan has to make following this:

-That the droid will support his weight

-That it isn't rigged to explode, or won't intentionally or unintentionally run into a building...or traffic.

-That the sniper who has her scope on him will for some reason shoot the droid and not his head.

-That when he freefalls as a result of this he won't hit traffic or the bottom of Coruscant but will slip gracefully into the padded leather interior of Anakin's speeder.

He clearly knew none of this. That's part of the suspense and drama of the sequence, Obi Wan made a rash choice and now he's hanging on for dear life and who knows what will happen or how he will get out of it. Obi Wan isn't going "its fine, don't worry, I read the script, er, saw the future cuz I'm a Jedi." He's going "SHIT, WTF am I gonna do here??" Thats where the drama comes from, if there is any.