I think that English, Spanish and French are the most important international languages because of several factors. But, perhaps, one of them is very important: they are very similar. They have the same alphabet and more than half of the words are almost identical.
I think that almost everybody in the world study one of these languages, for instance, English, and they can study easily, Spanish or French. That is a plus for Spanish or French.
If this factor is very important, these 3 languages will be also very important in the near future. And other languages, like Chinese, Hindi or Arabic will have more difficult to be true international languages.
At the same time, Russian or German are European languages, but not so similar that the first three languages.
In short, if English is the most important language, it is a good point for Spanish and French.
I think that almost everybody in the world study one of these languages, for instance, English, and they can study easily, Spanish or French. That is a plus for Spanish or French.
If this factor is very important, these 3 languages will be also very important in the near future. And other languages, like Chinese, Hindi or Arabic will have more difficult to be true international languages.
At the same time, Russian or German are European languages, but not so similar that the first three languages.
In short, if English is the most important language, it is a good point for Spanish and French.