The short answer is YES! You can get Google Voice working again, but you pretty much need to start over.
For those of us who set our devices up way back when, using the ObiTalk portal and then deleted our devices from the portal, it looks like we blocked a necessary upgrade/reregistration deal. Any Obihai devices set up with Google Voice back then used the XMPP protocol, which is apparently now officially dead, in favor of a new SIP setup.
Which means, at least as far as I can figure out, you have to start over. From scratch. Bye-bye all settings. Plan ahead. You will need to copy all your settings into a text file BEFORE you add the device to the portal, so you can copy and paste them back in, field by field. I don't think you can use a backup file, as that would most likely break your fixed Google Voice account. Haven't tested that, so just guessing.
Add your device to the ObiTalk portal and it will wipe out everything. (I haven't figured out how to stop it from doing this.) Then, add your Google Voice account(s) back. At that point you can manually add back all your other settings, either by using the ObiTalk portal via the "Obi Expert Configuration" feature or using the local web portal feature of the device. (You can't use both at once. Obi Expert blocks the local one.)
DO NOT delete the device from the portal. I did, a couple of times, and each time it dicked Google Voice and I had to start over again. I haven't tested what happens if you turn off Auto Provisioning and ObiTalk on the device itself before doing this. So, if you want to disconnect, try this early on, before you've added back any settings.
Let me know what happens.