Seems like this article gets always gets linked whenever SD cards on a Nexus are discussed. But quite frankly, it is not accurate.
If you look at the reddit source for the article, the quote from Dan Morrill that the article cites as the primary reason there is no SD card is actually not even referring to that. It is referring to why they had to switch from USB Mass Storage protocol to MTP. He is talking about the way older devices had their internal memory split into two partitions, one for apps, and one for media. That setup was a pain. You may run out of space for apps while you still have plenty of room in your media partition just sitting there.
But that has been changed, and now all your internal memory will accessible by either apps or media or whatever as needed. And this is not related at all to whether or not a device has an SD slot. Whether you have one or not, you will still have the single partition for internal memory.
Dan goes on to say that the actual reason they did not include an SD slot is because it would complicate the UI. For example you would have to decide whether to save pictures to internal storage or the SD card. And he goes on to say that they are looking into better ways to handle this and implies they would likely include SD cards again sometime in the future.
Android will continue to support expandable memory. New Nexus devices showing up without an external memory card slot likely shows Google's overall stance on what they really think about external memory. That doesn't mean other Android OEMs will stop giving users the option. You have choice.