What will happen to the other religions, I do not know, but I am sure that Islam will remain and will even strengthen. But let's be clear! If we mean the permanent saying of Allahu Akbar and Inshaallah as empty slogans, I hope it will disappear soon. I'm talking about Islam.
What are my arguments? My own life. I was born, I was a kid, I played and I wasn’t much interested in serious thoughts. This is normal like that. I learned; I adopted a knowledge that is the knowledge of the age according to the worldview of the people of the age. I entered the professional life and wanted to run a career with the knowledge I gained. I wanted to prove that I can become successful and rich with my knowledge. But I only used the knowledge I gained from school benches and from books of the age. I didn’t get on in life, but as an old man I had to realize there was a lot of trouble. There is no trouble with me, but with the knowledge and worldview of the age. No matter how I embrace this knowledge, as millions do, we do not assign ourselves for the benefit of each other. There is no intention that forges us together to achieve a common success, but we become competitors because we all want to benefit from something. Taking benefit of something or someone can also mean that I take advantage of situations, but inevitably advantage is taken of me as well. Most people are disappointed when they become old. Not just because of their own life, but because of the whole world. By then, one can clearly see that things are going like shit! The family, nation, civilization and whole humanity is a failure! There is no human regulation what can settle this situation. By regulation, I do not mean a law, but an internal attitude. It's lost. Well, this is the point where Islam is of immense importance. It is a real managing force. Provided we maintain and make the values of Islam available.

The second question comes. If Islam is such a very smart thing, then why we haven’t developed a corresponding -ism? Like socialism, capitalism? Why is there no regulation for a state management what is detailed at the level of ministries and different sectors prescribing what to do? This would be called Islamic regulation, in Arabic   حكم اسلامي (Hukm Islami). Although the word Hukm also means reign. But let's come back to the point. The point is that this is not the mission of Islam. Islam is not to create -ism, but to stand over the -isms. No matter what kind of -ism is just in force when shit people are in control. Islam is for shaping the human approach, the attitude. It is not Hukm but Nazeriya  نظرية i.e. theory, attitude. However, Islam has a complete system for that. It has theory regarding man, society, economy, finance, environment, broken down almost by every sector, but does not provide a specific description on operational level. This should be developed by the administration of a given place in the given age, after deducting it from the theory.
In practice, we are just touching the essence of Shariya, which today is a dirty word and incorporates primitive contents into its meaning that do not exist there. Although Shariya is an existing concept in other religions, including Judaism. Its synonym, the Law, is mentioned 69 times in the Torah. Obviously, this is not a human law. True, the Gospels never mention the Law. Maybe that's why the world is going in an unbridled riverbed?
The third question comes. What does Islam say about nationalism? Being a Muslim overwrites everything, but that doesn’t mean one can’t be proud of his/her nation. Christianity, for example, longs for the kingdom of Christ based on Scripture, i.e. the kingdom of God which is mentioned by Christ in the New Testament. In Christology it is said that Jesus Christ in his person is the kingdom of God. In Ecclesiology, the Church is considered the kingdom of God, or at least the kingdom of God here on the Earth. There is not a single word about the nation. On the basis of the Scripture they cannot even deal with issue of the nation. The reality, on the other hand, is different. Several Christian churches form opinions on issues related to the nation.
We know that Islam acts against the influence of the ego. But this is not mean that a person cannot feel national pride! If the ego entices one to represent supremacy, superiority under a national title, then the case is different!

In the Islamic view, i.e. in Nazeriya, construction does not start from borders, governments, and armies, but from the narrowest circle, the family. If there is an impairment here, the whole system is not worth a penny. So, family is the foundation. Families form a national community. National communities form linguistic, cultural units and the different national communities can create a civilization. The multiple civilizations together create the humanity, however the case does not end up here either, because humanity also has a duty towards the creatures and the whole world. I have told the division where Islam by Nazeriya builds a system where every individual can represent him/herself at all levels without being a competitor to another. I can belong to family, nation, language community, civilization, and humanity without being an enemy to anyone.
And here, too, Shariya is the key word. Because if we live in a Christian world order and there is no Shariya in Christianity, it may happen that people are deceived by referring to the loving heart of Jesus (peace be upon him) because of different interpretations of love, as usually everyone loves own self the best. Love alone is a huge concept and there are many opportunities for a subjective approach. Nazeriya breaks down into branches and provides a theory in order to compose family, nation, civilization, etc. at the operational level.
A believer knows that Nazeriya has an arrangement submitted to God. So, this is the decisive factor in our priority. But there are others as well, not just believers. Therefore, let us study our Islamic theories, and let other people to make study it with the eyes of outsiders as well, because it is important to realize that Shariya if it is fertilized by Nazeriya is one of the most pragmatic case management that exists in the world.
Thus, in old age, learning Islam, one realizes that Nobel Prize-winner geniuses, professors from Harvard can come however, they cannot give medicine to heal the disappointment of many aging men. All just push the world further into a deepening chasm. There is a way out. And this is my answer regarding the future of Islam. The question should not be asked whether will Islam disappear from the earth, but whether will humanity disappear from the earth? Islam can be a mean for survival.