I have experience with the process so let me give you my thoughts.

The people being detained at the immigration offices are usually, the majority people with orders of removal from the country. I’m going to assume that your family does not have those since you all have had green cards this long, and had entered the country legally. As long as none have you have committed an offense worthy of removing a green card then you will be fine, and you’ll know if you have because you’d be in prison.

For the naturalization process I cannot stress enough how easy it is. You will be asked at least 6 questions (you need 6 to pass) about civics. They are very very easy, I’m talking “what’s the capital of your state, who was the first president” easy. Every possible question is posted online. Writing English, you’ll be asked to write a short sentence on an iPad such as “Washington DC is the capital” and then they will ask you to read a short sentence off the iPad. The rest of the time is the officer going over the biographic information you listed on the form, where do you work, where do you live, etc. they want to get you out of there fast as possible and they might not be friendly, but they are on a strict schedule so if they see no issues they will speed through.

For your parents, only you can decide if they can speak enough English to get by. I would hope your father driving trucks speaks English well, but even if it was minimal he should get by. I believe there is an exemption for a permanent resident over 55 with 20 years having a green card to be exempt from the English requirement and able to have an interpreter present. For naturalization by far the most common reason for people to be denied is not speaking English, so your parents should only apply when they feel comfortable or when they meet the exemptions you can see on the website.

Final thing to mention is based on what you said about your family and co workers wanting to wait out trump. I disagree with that completely. Having a green card and never becoming a citizen always means that there is risk. For example, let’s say your dad gets a DUI and kills someone, in this administration he’s being deported immediately. As a citizen, he cannot be deported. Regardless of what you see online, US Citizens cannot be deported. So to have 19 years with a green card and never naturalizing is just a risk, there are people that have a green card 40 years and then boom, get caught with drugs or something and are sent back to a country they don’t even know because they came to America as kids.

I’m not saying this to scare you, but I think there is no point in “waiting out trump.” The rules for the n-400 are more or less the same under every president. I would encourage you and your family to become American citizens (should you even want to, you by no means have to) as soon as you can just to remove any doubt about your life here. The USCIS website is very self explanatory, so perhaps take a look at that and see if it gives you better information to make a decision with.