These projects cannot be guaranteed. All four are part of the recently established Pioneer Project, which promises to help relatively new researchers conduct experiments, but only if the cost of the mission does not exceed $20 million. Although this is cheap compared to many NASA missions, it may be lost if the newly selected concept exceeds the budget.
However, this challenge is part of the focus. Ideally, NASA can not only carry out more astrophysics research from limited funds, but also encourage people to take more creative ways to carry out science. It may reduce reliance on conventional satellites and the giant rockets used to get them into orbit.