Upload & Sell: Off
The Sigma is a tad sharper, has less CA and AF. Other than that I find the Zeiss more desirable in almost every way, boke, rendering, build quality, MF, ... If Zeiss does indeed release an Otus 35/1.4, the price will be so high that the Sigma is not even in competition any more, but becomes a budget option. I don't see that many people will be willing to pay Otus prices for a lens which is a bit better, but has no AF.
The most important characteristic of the Z* 35/1.4 is the OOF rendering at a bit of distance, in my opinion. I highly doubt that there are any other 35 mm lenses that could do this:
I don't even know if there are medium format lenses with the same AOV and equal DOF possibilities that does better in this respect. Of course they will most likely be sharper wide open, but the Zeiss does very well except for some purple fringing.