Politically speaking, is this realistic at all? Not only did the American public want revenge for Pearl Harbor, but there were some VERY powerful voices within the US military (Gen. MacArthur and Adm. King spring to mind) who either lobbied heavily for a Pacific campaign to retake the Philippines, or were fairly Anglophobic.
As has been pointed out, additional American naval power in the Atlantic isn't going to do too much, except in the realm of the Uboat campaign. But putting the American carrier fleet in the Atlantic doesn't do much to fight Uboats, and it isn't an option to strip away all of their escorts in the Pacific to go fight Uboats in the Atlantic, for the simple reason that it isn't acceptable to either a)put the carrier fleet at high risk or b)leave the carrier fleet docked in Pearl Harbor.
Additionally, putting Marines in the Atlantic also doesn't do much good. Sure, maybe you could use them as front lines assault troops against defended beaches, but at that point you have to either withdraw them immediately and replace them with Army ground forces (who now don't have the experience of a combat landing) or leave them in prolonged combat against forces they are ill-equipped to handle (I really wouldn't want to see the 1st Marine Division go up against, say, the Herman Goring division, for instance).
Next, you still have to send some level of Army forces to secure the lifeline to Australia (this is how the Americal division was formed), and you still have to send forces to Australia to shore up invasion fears. As I recall, weren't 2 National Guard divisions sent to Australia almost immediately? In addition, you still have to reinforce Hawaii.
My point is this. Discontinuing all major offensive operations in the Pacific except for a submarine campaign makes no sense, because it doesn't allow you to utilize your assets productively. The US Navy, not to mention the American people, aren't going to stand for 4-5 aircraft carriers sitting around doing nothing, but if you task those aircraft carriers with objectives, then you have to support them. You're not going to sail 2 American carriers within range of Japanese ground based air cover in 1942-43, without a plan to invade the island on which that air cover is based (pinprick raids on Kwajelein, Marcus Islands, etc., aside). It doesn't make any sense. The flip side is, with minimal diversion from the ETO, you CAN productively use the assets (USMC, US PacFlt) that can't otherwise be utilized in the Atlantic. Could less combat power be diverted to the Pacific? Probably - the problem is that a lot of the combat power that was strictly unnecessary (for example, 2 National Guard divisions to Australia or a huge Hawaii garrison) was seen as politically mandatory, not to mention we had no idea at the time it was militarily unnecessary.