I've been through it many times and expect to see many more. Both as the subject of an acquisition and as an acquiree. You just have to wait and see. If they're not immediately closing you down, there will be a transition period. Months to a year or more. That's where you need to be looking for a new job if that seems like a remotely feasible option.

With regard to your personal decision, do not trust what you're being told. The company wants a smooth transition and that means that the company wants to be the one making the decisions about who is working for them. They can and will lie.

The exception to this is if they ask you to stay on while they close out operations at your site. In that case they've already lowered the hammer, you're on borrowed time anyway, and it doesn't matter to them.

(Also - if you're given this option, consider it carefully before accepting. The folks I know who have done this have described it as a depressing and completely unpleasant experience. They all claimed they wouldn't do it again. If you choose to do so, ask for more money to compensate for the therapy you'll need afterwards. Be bold with your offer because it's a job that very few want to do.)

Generally speaking, the first thing that should happen is that the new company will harmonize efficiencies. This means cutting redundant departments, projects, or products. Expect to see a lot of strangers on site who are evaluating this. Non-specialized departments like finance, HR, legal, and support IT will be merged and streamlined. And do not expect that the highest performing department will survive. It's often the cheapest one who does. If the team in Kentucky can do a good enough job, it makes no sense for them to retain a higher paid workforce in DC. I've seen that sort of thing happen. (It's also sometimes a selling point for the company being bought. 🤮)

After that, it just depends on 1) why they bought you and 2) what they thought they were buying. If they find out that part of the acquired company isn't something they want but is valuable enough to re-sell rather than shut down, you may be in for a head-spinning transition between several buyers.

Overall -

The experience is a big shake-up, but I've gone through eight or so unscathed as a mid level employee. It all depends on lots of things outside of your control. It will help if you can accept that these things are beyond your control or beyond your ability to foresee. I can also assure you that there's a good probability that the people in charge won't be making good or sensible decisions.

Expect to see many of your co-workers jump ship, but that's not always a bad thing. Sometimes it's the kick in the ass that people need to make a change. That's often a very good thing.