From my understanding, the generals' loyalty is to the constitution, not the president. Had the insurrection continued for another hour or two, even more grievous acts could have been done, "forcing" Mr. Trump to declare martial low before the electoral college voters were ratified. That would have put the generals in a difficult position.
A feeble coup may be tried any time, but the constitution has clearly put Mr. Biden in charge. The generals will accept that. Such a coup could cause a lot of disruption, but not a full takeover.