They go through this every year. Contracts must be negotiated and signed. Last year, I don't think all the World Showcase restaurants and the CSR restaurants were on it until almost the first of the year. Disney only pays the restaurants a certain amount for each meal on the
DDP. The restaurants not owned by Disney may not like it, but if they don't join the DDP they know they would lose most of their diners, so they have no choice. Without the World Showcase restaurants the DDP would not be successful, so Disney knows they must get those restaurants in. Don't worry, both sides will do their part. They'll be in by the first of the year. They just have to negotiate. Both sides need each other.