Ahem ...... well...... yes they probably would. There are numerous instances of complete FU's by the NBN / Telco transition, and transitions from telco to telco post NBN.
Case 1 - two small - medium medical practices in a separate leased spaces in a typical suburban commercial area. Practice 1 is on the ball and transitions very early. Practice 2 is cutoff and is caught completely off guard scrambling to notify patients via mobile phones, no fax etc.
Case 2 - one owner in a small group / strata complex transitions early, other tenants cut off at the same time.
Case 3 - my personal experience - we have "Priority Assist" on the landline / NBN due to my cardiac condition - didn't mean squat in the transition - "you have a mobile service- what's the problem." 5 case managers and several weeks to resolve and no adjustments to accounts - "bad luck, what are you going to do about it" sort of attitude.
So many businesses have almost been ruined through poorly managed Telco / NBN interactions, not to mention how many lives may have been placed at risk through FU's.
Main problem is that when the Telco / NBN make the FU it can't legally be reversed under the Telco Act - as the service is deemed to have transitioned to the NBN once "cut over". No going back! These were a few years back as Townsville was a pilot.
One thing you learn quickly you must personally drive any complaint, because the telco & NBN blame each other and will not accept ownership of their errors. Recent ACCC $50M penalties imposed on Telstra (selling unaffordable mobile plan contracts to remote indigenous customers) and to be negotiated with 3 major Telcos over current NBN "speed issues" and misleading and deceptive conduct are only the tip of the iceberg. About time! Unfortunately most telcos are the same, when you are the "small percentage affected."