Jesus says in Matthew 26:11, "For you always have the poor with you, but you will not always have me." There is a lot of conversation about what this means and if Jesus was endorsing a social structure that keeps people poor. In the discussion I offer up the idea that Jesus said the poor will always be with you in the same spirit that he said, "Follow me." That is he said this as an invitation.
As long as people are following Jesus and giving everything up, then there will always be 'the poor." In fact, being poor is one of the categories Jesus says is blessed in the Beatitudes of Matthew 5. I confess that I am not the best at being poor in finances. Frankly, I am often embarrassed by what I do have, and tend to brag about the things I do not have. Even as a clergy person, I am not immune to Sin and in some ways. As a person with power, privilege and influence, I am often more in danger of the power of Sin.
Jesus knew the church would always exist, even after his death, because there will always be people to take the invitation of let go and follow Jesus. There will always be people poor in spirit and poor in resources - these are the ones that Jesus blesses and even says he would be dressed as in the final judgement (Matthew 25).