I just don't see this happening. As I wrote here some time ago:
"It would be easier for him to win the Democratic nomination than the Republican. The Democrats were desperate, thinking Truman was almost sure to lose--support for the "draft Ike" movement ranged from left-liberals like Claude Pepper to big-city bosses like Frank Hague to southern conservatives. So Ike if he wanted could almost certainly win the Democratic nomination, and if he did so would be very likely to win in November. It might be a little bit harder for him to win the GOP nomination, because while he was no doubt popular with rank-and-file Republicans, the party leaders--confident of victory--preferred a professional politician they would know as a "real" Republican. (By contrast, in 1952, many of these politicians turned to Ike as the only man who could prevent the "unelectable" Taft from winning the nomination.)"
To this I would add that even if the GOP leaders did find Ike an acceptable candidate in 1948, it would be only on the condition that he run as a Republican. They are not going to endorse an Eisenhower who is also running as a Democrat. (Even if you say rank-and-file Republicans could get Ike nominated over the heads of the party leadership, even many rank-and-file Republicans who liked Ike would only support him if he declared himself a Republican.)