It won't be released as a fully revised class, only maybe as a set of alternative class features
I believe that 5e rules designer Jeremy Crawford originally indicated sometime in late 2017 that the UA revised ranger would not be published in its current form. I'm not sure if it was mentioned on Twitter or in Twitch streams or elsewhere originally, but I don't think it was definitively stated at the time.
However, Jeremy Crawford did eventually make it clear in this Twitter exchange that any work on the UA revised ranger as a wholesale revision of the class was no longer occurring, and that at best it was a "possibility" that some alternative class features for the ranger would be released.
Crawford: If a year or more has passed since something appeared in Unearthed Arcana and that thing hasn't appeared in a D&D book, that thing is unlikely to become official. If it beats the odds and moves forward, you're likely to see it in UA again in a revised form. (27 Jul 2018)
Crawford: Regarding the revised ranger, I mentioned back in 2017 that we have no plans to release an alternative version of a class. That plan hasn’t changed. There is one ranger: the one in the Player’s Handbook. (28 Jul 2018)
Q: Are you still considering alternate versions of some of the class and Beast Master features, like you mentioned in the 11/27/2017 Dragon Talk episode? https://youtu.be/-vE28Saqcow (28 Jul 2018)
Crawford: Alternate features for multiple classes are still a possibility, but we want to do more research before we invest time in them. We don’t want our design to chase phantoms but real desires held by a large number of players. (28 Jul 2018)
Another user (a non-native English speaker) shared a screenshot of an August 2017 tweet in which Crawford had stated:
Crawford: Before the revised ranger becomes official, it needs further refinement. After that, we'll get it into your hands!
The user pointed out the contradiction with this tweet. In response, Crawford pointed out an October 2017 tweet of his own, which clarifies:
Crawford: In the end, there will be 1 ranger: the PH ranger. It will get alternative features. The official game won't have 2 versions of a class
Q: So a published version of the UA Ranger will be published as an 'alternate rule' for the Ranger? (10 Oct 2017)
Crawford: You'll be able to take feature X in place of feature Y. It won't be a whole different class. (10 Oct 2017)
In short: the revised ranger won't be published as a whole separate class. At most, it'll be a set of alternate class features, allowing players to swap out a particular PHB ranger feature for an alternate one - but the designers plan to do more research before they actually decide to do that.