The OnePlus 5 has become one of Halium’s unofficial official testing devices for Halium 7.1, so… yes. We will have Ubuntu Touch on the OnePlus 5.
And at the same time, OnePlus 3 was also used to test Halium 7.1, This was used before OnePlus 5 was released as an debug device, so expect this device also.
When will it be released? “It’ll be released when it’s ready.”

A priori OP5 seems a very nice device but OP5 buyers have found the screen is mounted upside-down and produces visual problems.

Instead of assuming the error, OP customer service is cocky, and is posting BS like [1]:

The screen so called jelly effect is caused by the user' eyes persistence of vision (visual staying phenomenon or duration of vision).

No need to say many forums are "burning" with this topic [2].

Maybe Halium et al. (including UBports, of course) should send an official statement to OnePlus and pressure the company to fix this nonsense.

[0] https://ubports.com/blog/ubports-blog-1/post/core-apps-backup-script-and-a-new-website-40
[1] https://twitter.com/OnePlus_Support/status/883047144021798912
[2] https://www.reddit.com/r/Android/comments/6lsne4/you_are_looking_at_it_wrong/