I don't know since neither Android nor ZTE has said anything...
I also have the ZTE ZMAX PRO and did receive an update to its Android 6.0.1 OS ...
The fact that the Cymbal T is a flip phone should not matter...
As for me, the upgrade is not that important... I have an old LG420G phone with a proprietary OS and it served me faithfully for 5 years before Tracfone shut down its 2g network on 01/31/17...
Seeing a flip phone with Android intrigued me and I bought it...
The Cymbal T is my "going out" phone since I can put it in my pocket and nobody sees that I have a smartphone and thus become a target...
I'm am looking to getting at least as much service from the Cymbal T, if not more...
Since I'm going to be 64 this year, I don't need the phone to be anything more than a phone, texting, and e-mail phone... I'm not into watching movies, videos, streaming music, or gaming...