GTX790 is expected soon, GTX880 unsure but IIRC the place that does the chips is finished with what they were doing and ready for AMD/Nvidia now.
i doubt that nvidia will launch a 790, if they were planning on releasing only 1 bi-gpu this generation, then they dont have time to R&D for another bi-gpu, that would take what like 6 months ? what's the point of releasing a bi-gpu at the end of the year, with a new generation coming at Q1 of 2015, that would give them less than a quarter worth of sell.
it's not profitable, unless they started R&D way back and they are gonna release it before the end of summer, but i doubt it




