Nah, Standard Oil isn't coming back. There are so many logistical nightmares and legal problems with merging two major oil firms that they won't want to repeat the process they went through ten years ago, nor will smaller firms be willing to buy the parts the DoJ forces the big guys to spin off. Just look at how Valero screwed itself by purchasing a good chunk of Exxon's California assets.

I don't think we'll see the domestic players merging but rather an increase in international joint ventures that effectively constitute a merger. Petrobras and Shell, TNK-BP and so forth.