Please, when you open a topic keep productivity & constructivity in mind.
Wild guesses can easily lead to panic (“I red in in the web, it must be true”) in the worst case, or a saltmine in the less bad case.
There´s always the possibilty to directly approach GBX-devs via PM over the Forum or per e-mail, to ask the people who are closest on the source. (though I doubt they have an ETA on server-shutdown yet either.)
Who said support for BB is withdrawn/cut off? There won’t be updates anymore, but support isn’t necessarily over.
As for the examples, there are still servers for Diablo II (2000) and Counter-Strike: Source (2004).
As for less popular games, Test Drive Unlimited 2 (2011) had both publisher and developer gone bancrupt in 2012, but the game had servers running upto 2016. Servers are still not officially dead, but this year they were more time down than up.
Test Drive Unlimited (2006) servers were up for 6 years. There’s still an online play for Grid 2 (2013).