This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. the property of a good or a commodity whereby individual units are capable of mutual substitution.

n. the quality of being capable of exchange or interchange

"The key work is "fungibility" -- the ability to move in and out of like systems and processes."

changeability    changeableness   

commutability    liquidity    replaceability    substitutability    transferability