Conceptually I love the idea. However I would skip the worldwalker pre-req and instead have it be a 1-2 refresh add on to a speed power(likely 1 and its just a homebrew stunt.). Call it Blink/Bamf/Whatever and have it function as needed for the character to short range teleport. I wouldn't even cut the speed(as I feel like in almost all cases it is very situational as a movement tool(IE, minimal bonus 90% of the time.) Add in a bonus +1 on defense rolls beyond the speed powers bonus to athletics and free up their movement and remove the attack penalty for moving when they blink.
Keeps it simple, allows for the concept, and is useful but not broken(Honestly feels balanced as a stunt.)
I feel the movement part itself is only minimally useful over the ones already granted by speed. It allows ignoring terrain and barriers, which is handy, but its rare that the terrain is especially awful, ignoring height via spiderclimb is -1 power and it allows you to cling to walls and stuff too(something I find more useful in many ways.) I have often found that outside of combat movement powers see minimal use to keep the group together as well so it isn't especially practical there.