I was listening to a discussion on NPR a while back(My apologies but I can't find the recording) and the speaker suggested that if the United States had begun losing the war he believed the US would have turned the internment camps into death camps like Nazi Germany had.
Of course that idea sounded hyperbolic to me but it got me wondering if there was a plan in place to deal with the Japanese-Americans if the US started losing.
For at least the first 6 months in the Pacific theatre we were losing. There was never a serious threat to the US mainland from Japan and they had no intentions of ever actually making a push for it. They simply hoped to knock out the Pacific fleet and force a peace, they had nowhere near the manufacturing capability of the US and both sides knew it.