Perhaps we're not really talking about the need for (2) data warehouses but rather an architecture of multiple distributed databases that are federated into a single logical data warehouse (think Microsoft's 'Parallel Data Warehouse' or what is now called 'Azure SQL Data Warehouse'), or within the same database you can support alternate levels of granularity for specific product lines using a separate fact table, or a vertical product oriented data mart existing parallel to the warehouse that feeds from the same ODS.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho