Well, you are going to have to distinguish between top tier providers like IS, Neotel and Telkom and the smaller Service Providers. They don't all have the same economic interests. Then there are the IECNS licence holders... who now have the capability to build their own networks.
You just need one of the ISPs to tap directly into Seacom using their own IECNS license and they can then resell that bandwidth over existing ADSL lines.
Price wars are coming guys... as soon as the ISP's end their existing contracts with current providers you will see prices starting to drop or packages starting to bulge.