Board Thread:General Discussion/@comment-4906037-20140305155055/@comment-6007020-20140309002527

All bankai can break, and remember that Tosen retains his sword during bankai, because anyone who touches the blade is spared from its sensory deprivation. Just destroy Senbonzakura's petals and Kuchiki is screwed. So far no bankai has become an intangible, unbreakable force. All of them retain a physical, breakable form, though most have impressive durability.