Doctor Syntax...So much smoke and mirrors.
What are you classing as the minimum throughput cut-off for FTTC here in terms of the coverage area? 10Mbps?
How are you measuring this 30% take up of FTTC? Because its a distance dependent product, speeds drop of rapidly the further from the FTTC cabinet. Of those 70% not taking the service, how many are at the outer extremes of the coverage of the FTTC cabinet, where they aren't going to see any real benefit to paying for FTTC due to very low throughput.
A large percentage (most) of the 30% taking up the service are likely to be the ones going from circa 17Mbps+ ADSL Sync Rate to close to maximum FTTC 40/80Mbps, where the gains are greatest.