The last rumors I saw running around indicated that when EPA approval for diesels was delayed, BMW didn't know what the EPA might've required them to do for certification. Therefore BMW didn't bother finalizing the diesel vehicles for US production ("homologation"). With EPA approval in hand they can get all those little details finished and get production set, but that takes time and BMW is apparently focusing on getting the 328d ready first.
The 535d is available because it is MY 2016 F10 535d, which continues in production through October. There is no MY 2017 G30 535d on the public ordering guides, and no final word as to whether that car will even make it to the US. If it does, I expect it won't be until MY 2018.
I've heard January 2017 for the X5 diesel, but that is in no way official. BMW sells more diesel X5s than V8 (50i) X5s in the US, so I see no reason why they would kill the diesel now.