Basically Vivendi is running around pushing alot of it's developer's shipping dates to 2004... not just Valve.
Interplay is dumping them and probably gonna sue for missing back payments. Interplay also vowed to get their games out in Q4 2003, even if they have to do all the distribution THEMSELVES.
If HL2 will in fact be ready for a 2003 release, could Valve afford to distribute it themselves?