I think that had Google acquired GoogleVoice, it would have ended their other service, the GoogleVoice. Since both programs were SMS-based messaging service, I do not think there would have been any purpose for Google to have both. So it would only have been logical for Google to end one service.
I think Google voice would have hung around, or it would have been integrated into whatsapp--or vice versa. I wish Google would have gotten Whatsapp, instead of Facebook. I'm just dreading whatever updates are going to happen on Whatsapp now. Facebook is the worst social networking site ever made, and it ruins what it touches.
I think because Google Voice is so popular that it would have been silly for Google to have ended it if they had acquired WhatsApp, what would have been more likely is that the Google would have merged the two services and user bases together into one service and it would have been more likely for Google to merge WhatsApp into GoogleVoice.
If Google had acquired WhatsApp, it would have not have meant the end of GoogleVoice, which also offers SMS-based messaging services. A lot of people are used to using GoogleVoice so I think that they would have been not so happy about switching over. I think that Google would have kept both services.
If Google had acquired WhatsApp I don't feel they would have ended GoogleVoice, that would not have been a wise business decision, but would have in turn integrated WhatsApp into the functionality of GoogleVoice. The SMS functionality of GoogleVoice would have benefited for the expanded flexability offere by WhatsApp's services.