We can be quite sure that Canon has given tis task a lot of priority.
And I don't think it will take too long until we get a "ta-da" from them. But will it be a 7D2? Their other high-end cameras - 70D, 6D, 5D3, 1Dx - are all very recent. Or do they start a new 3D line with 30-40 MP to match against the D800?
An EOS 3D still sounds nice. Or why not a straight copy of the A7R? Small and light, with top image quality, high resolution and loads of DR at base ISO.
If Canon is afraid that 5D3 and 1DX users will complain, then they can just cripple the AF-features a little bit, set the FPS to 4, and give it a tad worse high ISO performance. That'll do it.