I don't understand why this is a problem. We are moving through demographic transition, as the world reaches its carrying capacity for human populations. So, we are safe from overpopulation crisis, from future unemployment crises, etc.
I don't think the solution should be to prop birth rates back up, necessarily, but we do need to consider how to deal with the economic consequences of this demographic transition, and I don't think any mainstream politician is currently willing to deal with a world that doesn't experience constant population growth.