Interesting, I found a feature request for a "play next" on their community forums [0]. They responded:

> We've discussed this feature in-depth internally and also carried out a variety of tests with different groups. Based on the results we can confirm that for the moment we won't be changing the existing way queueing works. As we don't have any immediate plans to implement this, we'll be changing the Idea Status to Case Closed.

Added my +1 and keeping my fingers crossed that they revisit :)

[0] https://community.spotify.com/t5/Closed-Ideas/Queue-Queue-to...