I think you're actually wrong about VC goals. Yes VCs look for acquisitions, but acquisitions only really move the needle when they're really big (>$100m). Anyone acquiring for those amounts aren't going to shut the product down.
It's pretty easy to name any number of >$100M acquisitions that have been shut down. Regardless, that's only a goal of VCs: there's no shortage of VC-funded companies that have been sold for far less than $100M when they couldn't raise the next round at a palatable price.
No startup company can make a defensible claim that their product will be around for the long haul.
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.
I don't think the point is only about the product going away. If Inbox is acquired then it's no longer 'the email company' but the whatever-the-acquirer-wants company (which may well be advertising).
