Once withdrawals were turned off for an extended period of time, recovery was not possible. Volume dropped to nothing and trust was completely broken. There's no point in WEX coming back now.
They'd probably still find users willing to flock to their exchange if they resumed operations and started repaying their debts. There aren't that many KYC-less exchanges, with minimal KYC for fiat deposits/withdrawals as was the case with btc-e/wex. At one point you could even make large deposits and withdrawals in cash (I think the minimum was $50k USD for EU countries).