Hi Antoni, I think that stock photography is much more oriented on business subjects and still life, because these kind of photography could be used to express in a clear way a concept or to isolate an object for post-production creative processes. Landscapes are very beautiful, but could have a minor potential in terms of marketing language. Nevertheless I believe that if one don't takes pictures for money, he should continue to photograph what he really likes. As a matter of facts the real satisfaction is the picture you have realized and the relative appreciation. So don't give up, and do it for fun!
Wish your best,