Those liberating forces at Google bannered under Google Takeout is set out to liberate data and now they have added Google Voice to it.
There are many other products available at Google takeout but with Google Voice addition, you and I will be able to takeout any data on the Google Voice, from call histories, Voicemail messages, Greetings (exported to MP3), TEXT Messages or SMS (as micro formated HTML) and the forwarding phone numbers (as vcards).
This is good if you need to use the these data elsewhere but I think Google Voice is a good place my data, unless something drastic happens.
See the video for some explanation and fun.
Google Voice Blog: Google Voice for Takeout