Here's a fued idea. The legacy stable becomes huge with about dozen multi generation stars (very possible) obviously led by Orton. The stable crosses over all 3 brands and runs rampant on the WWE. The stable is extremely inclusive, and only generational stars would be allowed in. Newer superstars will get a big push by associating themselves with the stable (evolution anyone?) and the WWE is in chaos. Now, instead of having a stable like WWE vs. The Legacy (a nod to WCW vs. NWO) or Newer Guys vs. Older Guys (like in TNA and at the end of WCW), tag teams become more prevalent and form unlikely alliances to combat the Legacy. With these unlikely alliances, new rivalries are started and small stables are created. Heel wrestlers, who would want to get into the stable and being that it's inclusive, it would create even more tension and heat including plenty of heel vs. heel matches. This massive fued involving the Legacy would last at least a year, and would eventually disband. The no name guys living in their father's shadows will be much better superstars and would feud with each other afterwards. Speaking of fathers, this would also give great opportunities for some of the older guys that are Legends to come in and align themselves with or against the Legacy. Orton's legend killer attitude would play into that quite nicely as well. These are the guys that would be involved in the stable:
Orton
Manu
Rhodes
Dibiase jr.
Snuka
Umaga
Neidhart
Carlito
Primo
DH Smith
Chavo
TJ Wilson and Joe Hennig (if they get brought up to the main roster)
Mysterio would be heavily involved due to his generational status and there could be a tease as to if he would join the stable. He ultimately won't, as the stable is a heel stable, but there could be a lot of suspense surrounding the possibility plus Mysterio could take part in serious tweener moments involving face superstars. His involvement will give him a push back to the main event as well.
In terms of title feuds and "getting all the gold," you've got Orton vying for the world title (either one), guys like Chavo, Umaga, and maybe Manu going for the ECW title, Neidhart for the women's titles (she could be both divas and womens champion, maybe even unite the two and get rid of that damn divas title), and the rest feuding for the mid card and tag team titles. I think it would be absolutely incredible if they brought in some older guys who were big in the attitude area, especially the Rock. There's enough legacy out there to really make this angle huge and completely revitalize the WWE.