I had some Dell stock in a brokerage account when it went back private. It was just converted to cash automatically.
Regarding being an employee at a tech company, usually you get RSUs. They vest over time, usually a 4 year period after grant. Stock you already have granted will convert to cash and you will owe taxes for capital gains if applicable. You will already have paid income tax at the time the stock was granted.
RSUs that are not vested often accelerate, meaning all RSU become immediately vested at the time of sale and are converted to cash. This is likely where the "tax burden" comes from that was mentioned previously.
That said, RSUs can also be structured where they continue to vest on the same schedule but are just paid out as cash at the company sale price.
Worst case is that unvested RSU are canceled. If that's done, there would likely be another bonus program replacing them. In tech companies a lot of compensation can be in the form of RSU, so no software engineer is going to hang around for a base salary with a 401k match.
