Population Growth

Hang on a second! An independent senator from Australia says the taxpayer base will be halved in 30-40 years. This has massive, seismic implications for the remaining population. Your taxes have to double for starters! How are economies going to negotiate this? Government will HAVE TO get smaller. Less services. Slashed defence resources. The ability to defend a country is going to halve. I thought we had to cull the population? "We're wrecking the joint"! Remember?!?!?
Half the current populaion in 30-40 years? What!?!? Who's lying to who here!?!?! And why?