I got the dreaded NBN letter.
Have been a relatively happy Optus cable customer, so decided to stick with them for NBN.
I got a bonus for signing up to Optus NBN deal today - I got 50% off the monthly charge for a mobile sim only plan.
You can pick the $59 per month plan (contract for 12 months), and get 50% off - so you only pay $29.50 per month. That's the 80gb/mth data in Aus, with 2gb zone 1 roaming.
Or the $79 per month plan comes down to $39.50 per month - that's 120Gb/mth data in Aus, with 4gb zone 1 roaming.
Since I had rolled off the $39 Telstra deal from last year with the JB gift card, this seems to be a pretty good deal (pay 50c/mth more, get 100Gb more data, some international calls, plus some global roaming data if I happen to need it).
Mobile signal coverage may vary in your area, but I'm in Sydney metro and they are all about the same for me.
Edit: I rang the NBN sales line to get this deal, and they offered me this as a bonus when trying to sell me the NBN deal as well.
never offered me those deals when i signed up