I wouldn't say this is the defining quality of a startup, but it is an almost inevitable consequence of the defining quality, which is growth. A fast-growing technology company will get acquisition offers, whether they seek them or not. And one that grows sufficiently large will have to go public, whether they want to or not.
And one that grows sufficiently large will have to go public, whether they want to or not.
I'm curious, what is your reasoning here? Because it will be acquired by a public company (e.g. Microsoft or Google)? Or just because investors will want a means to exit?
It's too bad the use of "the exception proves the rule" in cases like this is a solecism, because this would be the perfect time for it. SAS is the closest thing to an old-style industrial company in the software business.
(In "the exception proves the rule," proves is used in the older sense, meaning to test, not the newer sense, meaning to establish.)
