The G20 Hamburg Action plan called on “the IMF to further enhance the effectiveness of its lending toolkit in line with its mandate, including considerations on a new short-term liquidity instrument and a new non-financial policy cooperation instrument”, and I understand that this work is receiving attention at the highest level in the IMF.
Indeed, while the LCR requires banks to hold sufficient liquid assets in good times to meet their outflows in a given stress scenario, it implicitly recognizes that if things turn out even worse than that scenario, central bank liquidity support will be needed.