I can't really picture Sheamus working well in a stable. I see him more as a solo performer. Maybe eventually I could see him forming a tag team, but I would picture that with someone who's got some definite size on them. If I remember right, Delaney was considerably smaller than most of the other wrestlers in the WWE. Again, I could be wrong.
While Finlay definitely has a purpose in the WWE, I don't think that purpose will fit well with Sheamus' purpose. Finlay is a teacher and someone who can put over new workers on their way into the upper midcard. Sheamus doesn't need a teacher, since he's now fairly well established in the main event, and thus the need to be put over Finlay is gone as well. In addition, I don't buy Finlay as a serious title contender at this point, so the only possible role I could see Finlay having in a stable would the Flair role from Evolution, and the Irish Evolution doesn't really seem like a plan to me, especially when they quite easily do a European tag team with Sheamus and Barret, who work together better, in my opinion.
As for Delaney, I believe that I've read he's doing quite ok in Chikara, or at least has a better setup than when he was in ECW jobbing to Dreamer in their feud. Sure, you could bring him back with the gimmick of, I've trained hard while away from the WWE and now I'm a bad ass, but honestly, they have enough new talent that they are going to need to find something to do with before they really need to look into bringing Delaney in. There are the 7 Nexus guys, at least 4 from NXT 2, the Usos and Tamina, and possibly some NXT 3 guys if they decide to run that. While I am all for the WWE trying to establish new stars, they have brought in quite a few over the last year, and the Creative team has a hard enough time keeping people occupied, especially once we regain any guys who are out due to injury. I can quite easily see Delaney getting last in the shuffle fairly quickly, so I think the best bet would be to leave well enough alone, and let him continue to work in Chikara.