It seems that Red Bull have abandoned the British F3 championship as one of the development series for their Red Bull Junior Team. The path followed by Alguersuari, Ricciardo and Vergne was FR 2.0, then British F3, then FR 3.5.
Of the current batch, Sainz Jr has moved from last year’s British F3 to GP3, and Kvyat (having competed in FR 2.0 the last two seasons) will be joining him. da Costa will return to FR 3.5, so obviously that remains the final stepping stone, from Red Bull’s perspective, prior to F1.
Whether Red Bull was motivated to leave the British F3 championship by the declining depth and standard of the series, because of the increased power levels which the 2013 GP3 cars will enjoy, or a combination of both, is unclear. Whatever the explanation, I’d be surprised if Red Bull junior drivers returned to British F3 at any time in the near future.