He's a new face to feud with the Shield, after he "feuds" with the other men who ar in the MITB match, presuming he's in it, which I am.
It's a story that writes itself, really. RVD, gone for 6 years(as WWE won't acknowledge his time in TNA), gets an automatic spot in a match to potentially cash-in for the World or WWE Title. As much as they're illogical in many ways(The Shield), this would be a logical one, I suppose. One could argue that his veteran status and his accomplishments merit a spot in the match, and I would tend to agree. But the Shield? It's fodder. A returning star who was the first duel WWE/ECW champion getting a spot strictly on what he's done in the distant past, not what's he's earned? What better way for 'Shield Justice', having a semblance of logic, but going overboard, likely with RVD being either cost the MITB ladder match, or Mr. Monday Night being re-introduced to Monday nights with a triple-powerbomb from them?
I can't say I'm terribly excited by RVD coming back to WWE. Yes, he adds a semblance of star-power, but he also costs and gets by on the minimum as much as he can, at least that's what he did in TNA. Perhaps it extends his career by 5 years, but it shoudn't equte to a push of any kind unless he actually puts in real work. This isn't HHH or HBK or The Undertaker, this is a career upper-mid-carder.
So, who else to bring out that "fire" in RVD then an attack from the Shield? Unfortunately, it's Ambrose(who's very good) as US Champion rather then Rollins, because I believe the two could tear the house down in a U.S Championship feud. At this point in his career, RVD is 42. He shouldn't be winning major championships or challenging other veterans for them, he should be putting younger talent over. The Shield acquitted themselves from their one hiccup rather nicely, sweeping their matches last night, but their feuds with Team Hell No and Randy Orton feel played out at this point. RVD supplies a fresh, new face that they have yet to cross paths with yet, and the story fits.
If they don't want to go there, there's always Randy Orton. If Orton is a heel at this point, or even the same character he is now, they could always reference the "reason" RVD left WWE. Orton bet him up after ONS 2007, punted him in the head, and RVD hasnt been seen since as far as WWE is concerned. WWE dipped into several years in the past with the Orton/Punk feud from 2011, so it's not illogical they could do it here.
I've always liked RVD when he's been at his best. If he brings an inspired effort once again, he's very welcome addition back into the fold for WWE, and me personally.