From my easy chair on the other side of the continent...
They’ve been sending the maximum flow through the main spillway for a few hours and the flow through the emergency spillway has been reduced to near nothing.
So they should be able to run the main spillway at the max for 4 or 5 more hours and have the lake level down enough so they can fill in the main spillway with rock and concrete before the level got to the top again.
Then they can let water out the main spillway fast enough to keep the level safe- below the emergency spillway- henceforward.
So, it looks good.
Don’t see much of a way to repair the spillway at this time, since it has cut a huge hole to the side of it now.
They’re letting out, 100,000 cfs, but there is still 50,000 cfs coming into the lake
As a retired contractor, viewing the pictures I have some observations. If the main spillway runs for a few hours and lowers the lake where the emergency spillway is no longer draining and damaging its outflow, as you say, the main spillways damaged outflow structure could have its gaping sinkhole filled.
The problem is access. There is no road or stable access to the damaged spot. Instead, big rip-rap boulders, high-strength / early set concrete and massive helicopter delivery is the only feasible method I can see if the window is only about 48 hours. Even then, that spillway running again will tear out all the temporary fix in short order.
How do they get the concrete and rock to the hole? There is no access to it.