To be honest, a spring 2013 release would not be bad.
Nintendo could avoid direct competition with Halo 4 and the new PS3 model.
Also It would give more time for developers to finish unannounced projects for Wii U.
Nintendo doesn't consider Sony and Microsoft competition. I'm sure they care about Halo 4 even less. Iwata has stated this many times.
Nintendo's only consern with Microsoft and Sony is the copying of their products.