Not at all. 4G - You have the Wireless Broadband - either 200 or 500Gb (cant share data pool) or Mobile Broadband up to 75Gb (can share data pool with postpaid mobiles/mbb on same account) 5G - 5G Home Broadband - Unlimited Data
Interesting theory. I'd suggest that the NBN for the moment is doing quite well (and that coming from someone who is bitterly disappointed the FTTP rollout was shut down. Its a massive project and still being rolled out. Most of the population has seen a big boost to to accessible speeds and some new technologies should see those increase further over the next few years.
What is sad is that half the nation is still on FTTN (i.e. ADSL++) and after spending $50 billion a significant number are still only just getting ADSL speeds (with little hope of more). No doubt we will eventually get back to the FTTP plan but that might be 10-20 years away. In the mean time the NBN is only barely sufficient for today's needs.
FWIW the government did indeed take over all land based telecommunications for the NBN (some good reasons for that) but they have left the mobile area to the Telcos which is why they have been investing so heavily on new 5G technologies.