Even if it's VC backed, there's little reason for the VCs to prevent them doing a non-takeover tender offer in order to allow employees to cash out some (often capped) portion of their vested options and let in a new private shareholder.

And as someone who went through an acquisition exit in a just-shy-of-unicorn startup by a very big dog, yes, everyone's/VC's aversion to IPOs is definitely making it easier for said big dog companies to acquire people who in the past would have been shoe-ins for excellent IPOs.