In countries where they've already pretty much completed this (Switzerland for example) the biggest headache has been elderly customers. It takes a lot to convince them that :
- If they haven't got it yet, they will need broadband.
- They will keep the same number (they never believe that bit - how can it possibly move to the internet?)
- No that favourite telephone they've had for the last thirty years definitely won't work any more1 but the new ones are very nice
- The anxiety attacks they are having about possible disruption to what is often their main link to the outside world will pass in time
These are all serious and genuine concerns, and the answer has been to deploy very expensive teams of support staff to go and visit this segment of customers to help reassure them and handhold them through the transition. Warning, costs will go up as well as up.
1) without some additional non-standard equipment at at significant additional supply and setup cost.