。
Everything hinges on the outcome.
Literal
All-things [topic-は] that result [dependent on-いかんに] hangs.
Two formal/literary elements. いかん ('the how-ness,' 'the nature of') is a classical noun meaning 'the state/outcome of something' — almost always paired with に (いかんに) in the set pattern Xいかんにかかる ('depends on how X turns out'). かかる here means 'to hang on, depend on.' A stiffly elegant sentence.