We've had Vonage for about a year or two and have been very happy with the service. So in that respect I hope they survive. But with Skype being so much cheaper for the same national unlimited service I kind of hope they do go under. It's the only way I could talk the other half into the trouble of getting a new phone number.
I too hope they stay in business, or at least provide a planned migration to a new service for clients. We, VoIP users, do not need another SunRocket black-eye and I'm quite happy with our current (not VG) provider, currently enjoy a high WAF.
If VG shuts down then the VoIP providers will again be flooded with new business, but worse this time due to the (perceived) (in)competence of their user base.