Not with a dream like that. It's a strawhat dream if there ever was one, and it's intrinsically tied to Robin's dream.
Why would he go with the revs when his dream requires Laugh Tale? Assuming that's where the truth of the ancient kingdom is, as many do because of Robin, Vegapunk needs to be on the pirate king's crew to achieve his dream. Vegapunk even fits the mold of his dream and fighting style being tied to his role.
I'm definitely including Lilith or Shakka when I say Vegapunk. Could be the original, could be some form of the alts, could be all of them and Vegapunk fights like Pain from Naruto. But some form of Vegapunk is joining for sure. As far as being too fast, many Strawhats had a role and a dream 2 or 3 chapters after being introduced. We just had a lot of candidates who weren't perfect lately so we ended up with a lot of "it doesn't have to happen right away" arguments. He does still need a flash back and a villain for Luffy to defeat, which may not be Lucci.