Spanish language learning forums - ganancias que van a ser mayores

¡Hola!

Here is the sentence from an exercise book, the answer key has van:

Creemos que la temporada turística este año resultará en ganancias que van a ser mayores con respecto al mismo período del año pasado.

We believe that this year the tourist season will result in / generate / yield earnings that are going to be greater / bigger regarding / with regard to / in relation to the same period of last year.

Would you advise if the present subjunctive may be substituted for present indicative in the adjective clause?

My reasoning is that

the situation in question refers to the future;
the antecedent (ganancias) is non-specific (no article) and
an element of anticipation is present.

Creemos que la temporada turística este año resultará en ganancias que vayan a ser mayores con respecto al mismo período del año pasado.

Thank you.