NX500 still worth it in 2020?

I wouldn't suggest the NX system to a lot of people these days, but you seem like a very educated person on the subject matter, and probably for you is the cheapest solution.

Where are you from? The prices of used NX are insanly cheap, also, how do you manage to be a professional with a 350euros camera? That is quite an achievement!

I am not sure what kind of job you do, for landscapes the 12-24 and the 16-50PZ are probably enough, even though, a more professional kit is the NX1 with the 16-50S, which is a professional grade lens with a professional grade camera (better ergonomics, viewfinder, protected by the elements, bigger battery, e.t.c), for a lot more reasons than one.

The 16-50S can be amazing as a kit lens (there is some sample variation going on, but the most I have seen are very good, for what they are) but it's not even close to the S lens.

The PZ can be a little hit or miss, and you have to test it to see its limitations, because there is not a pattern among them (from my experience, reading, and samples I have seen).

The 30 is incredible and an amazingly small combo with the NX500. The 50-200 is a surprisingly well build and performing cheap tele, probably the best such a small tele I have ever seen, it goes down in sharpness after 170mm or so usually. Sample variation applies (with every brand, with every cheap lens).

My favorite lenses are the 45mm, 10mm and the 16-50S. These are the ones I use more, the 12-24mm also.

The 18-200 is a no go for high resolution photography. I may have a bad sample, but it is my least favorite lens, good for video though, and easy to carry on holidays (is on my NX500 these days) as a do it all lens, but not on a pro job (except when I shoot inside boats that I do not want to destroy my better lenses..).