Ultimately you have to decide. But consider this: it seems to be a reflex of many to opt for wide lenses when shooting landscape. But I found that oftentimes, having a longer option will give you a lot of creative flexibility. They let you compress the vast landscape into compact frames, finding lines and silhouettes, letting you isolate interesting scenes. All the while a wide lens will oftentimes leave you with a lot of foreground that is overrepresented in the image while the background, e.g. a mountain ridge, might seem smaller than in real life.

Don’t get me wrong, you can get great results going wide, but the equation landscape=wide lenses is not always true. Since you have 16mm already covered, I would consider adding a longer lens to your kit. When thinking primes the 90mm comes to mind which is superb. The 55-200 is also a great lens.

It’s just a thought. The 16 1.4 is supposed to be superb, and if you want to shoot nighly campfire shots or closeups of local flora you‘ll not regret getting it. But teles have their spot in great landscape photography. Google telephoto landscapes for inspiration.

Sorry for being the devils advocate here... ;)