Your loans may or may not be marketable if they lose their QM status – it will depend on what the investor requires. But in reality it will be most likely be more difficult to sell loans that are not QMs.
And you may be thinking about the temporary QM – Special Rules option. See page 31 of the CFPB’s ATR/QM Small Entity Compliance Guide linked here: https://files.consumerfinance.gov/f/201310_cfpb_atr-qm-small-entity_compliance-guide.pdf