Employees and employers are always in a war of information. Employers work together with their crony class traitors (like HR) to come up with plans to increase profits and mitigate losses based on what they can glean about employees. They are asking you all these questions as a form of intelligence gathering. Maybe they’re trying to get a handle on where they most need to begin recruiting. Maybe they’re trying to get a handle on why people are leaving. Maybe they’re using the information gathering privilege to intimidate people. Maybe it’s something else.
Either way, it’s rarely in an employee’s interest to provide accurate information like this to an employer. If they were actually worried about people leaving they could just raise salaries and figure out if there are specific working conditions to improve like getting rid of abusive managers or changing work responsibilities. But those aren’t the questions they’re asking.
The only question is how to avoud questions or lie. Avoiding is best. “I hadn’t really thought of that. What is your opinion?” is a good default. Or, “have other people been talking about that?” If they try to force an answer, just lie. You see yourself there in 15 years, whatever.
This may be a sign that they feel weak in their labor market, though. I think this is actually a good time to ask for a raise and promotion. It’s also a good time to start looking for other jobs, as a big exodus of people that they’re not handling appropriately means everyone’s working conditions are probably going to get worse. They seem to be in complete petty tyrant mode.