Selam Sunnybebek,
"olmayacaklardır" yerine "Umarım ki hacker değillerdir." dememiz daha doğru olur bence. Çünkü "espero que sean.." şimdiki zaman ile yazılmış.
But aren't both variants possible?
"Umarım ki hacker olmayacaklar" and "Umarım ki hacker değiller". Because "sean" is used in Presente de Subjuntivo, which refers both to present and future tenses.
Grammatically right, but I guess as "espero" already gives the statement about future, about an expectation and desire, it is appropriate to use present tense in the whole sentence. Also, the sentence with "olmayacaklar" doesn't sound very natural in Turkish. About the expectations we never use future tense I think
Like in English as far as I remember, in some cases when we use "hope" we don't write the sentence with "will" but I am not sure about this , or am I wrong?