I manually updated my OBi110 from 2872 to 2886 from the local device (thanks for the instructions/link!). I was able to register a GV account with the ObiTalk portal using the new version. (SIP service on the second line never stopped or had an issue.)
I have a second OBi110 with 2824 that continues to chug along without issue on the same GV account. This one did not need the update.
Regarding the future, the handling of this (unofficial?) upgrade/service fee does make me worry about ObiHai and the future of their SIP/GV devices. I have purchased and manage a fleet of seven OBi (100, 110, 200, 202) ATAs. I have recommended them to many people, and was looking to purchase a few more to help people understand the technology. That said, I will keep recommending the devices, albeit with a strong caveat that free may only be for today.
The ones who are more nervous about 'free', I point to VoIP providers like CallCentric or
voip.ms.