It will probably raise the retained earnings threshold and like Calabria said set out mile markers for the companies to achieve while giving FHFA more power and flexibility.
An interesting idea I saw floating around said that the seniors might be written down to near-nothing rather than nothing at all, and that the dollar-for-dollar liquidation preference increase as FnF retain earnings might be kept, at least until Treasury truly deems the seniors paid back (as if they weren't already).
That would mean that any delay to the capital raise wouldn't actually build capital at all, and thus FnF would have every incentive to do a capital raise ASAP. One big enough to pay off whatever part of the seniors that Treasury deems necessary as well as raise FnF's capital levels. That would cause the juniors to hit par much sooner than some expect; they will be money good when capital is raised.