Not sure where the B2B constraint came from. That's a little more challenging, because B2B companies are more likely to have revenue and enterprise sales channels, etc., worth preserving, and it's not particularly relevant to your thesis (that products from VC-backed companies are less likely to get shut down).
Still, here's a few that came to mind where the product has been shut down or changed sufficiently to be the equivalent for many customers:
dMARC
FeedBurner
AuthenTEC
Face.com
TellMe
Wildfire
I'm sure I could come up with a few more if I thought about it a little longer. I'm pretty sure these are all >= 100M.
Vendor reliability is a problem at all levels. If you don't have a multi-year maintenance contract, all the more so.
Still, here's a few that came to mind where the product has been shut down or changed sufficiently to be the equivalent for many customers: dMARC FeedBurner AuthenTEC Face.com TellMe Wildfire
I'm sure I could come up with a few more if I thought about it a little longer. I'm pretty sure these are all >= 100M.
Vendor reliability is a problem at all levels. If you don't have a multi-year maintenance contract, all the more so.