Almost.
(Minister Bones reveals her survival and the characteristics - though not location - of her government-in-exile not long after, coordinating with the members of the remaining free wireless station to disseminate information, especially to anyone who didn't successfully make it to Hogwarts, or who is a more quiet supporter of the resistance. She encourages those still operating within normal wizarding society to keep themselves safe but to be as non-compliant as they can, especially in ways that hinder the new regime.)
(Voldemort brings a siege against Hogwarts. He doesn't have nearly enough loyal Death Eaters to maintain a cordon, let alone a siege the wizards sheltering within the castle can't just overwhelm with a bold enough rush.)
(He uses Dementors instead. A roiling cloud of them, pressing constantly against the edges of the wards, bringing an intense pall over the grounds. Many of the sapients within the Forbidden Forest move in closer to the castle itself, away from the worst of the aura of misery. The Dementors don't sleep. They don't get distracted. They don't get bored. They can't be tricked or affected by conventional magics. There's enough that even the strongest Patronus or the angriest Thestral can't force them back for long. They can't be chipped away at in a war of attrition by defenders safely ensconced in Hogwarts' powerful wards.)
(Anathema directs the Chamber to form a tunnel, deep underground, under the water table, well reinforced against inundation, out to the edge of the wards. Headmistress McGonagall carves a distinctive room out of the bedrock past that, condensing the stone into a dense shielding. They can Apparate in and out of that. It's not very pleasant, or very good for bringing in supplies, even after Anathema widens the path enough cars can drive it. People seeking to flee to Hogwarts can't Apparate to it on their own, and they have to rush to disseminate information about the siege to the wider society so no one will try to come without an escort. There's an extreme risk of someone tracing an Apparition into it and gaining access to the castle; Anathema sets up traps and remotely activated security gates along the path. It's something, though.)
(Hogwarts' grounds become farms. Professor Sprout uses magic to make growing conditions as ideal as possible - easier with the muggle seeds - but can't increase growth rate too much without compromising nutrition. Chickens range in pastures magically protected from predators, eating all the scrap Hogwarts' inhabitants can't. They coordinate with the Black Lake's inhabitants to start fish farms. They bring in a trickle of more supplies, more seeds and cuttings, live fruit and nut trees a few times, more livestock through the Apparition point Anathema made. They ration.)
(Attacks against muggleborns and their families who were caught outside Hogwarts step up. They convince some parents of young muggleborns to move to Hogwarts. They don't convince enough. Some 'blood traitors' and 'sympathizers' who didn't make it to Hogwarts are publicly tried and then either given harsh sentences or executed, depending largely on if they accused or betrayed others. Indiscriminate attacks against muggles as a whole begin. It sounds like Voldemort's not really bothering making the attacks seem non-magical, though the Statute hasn't been broken yet.)
(They try to track Voldemort's remaining Horcruxes. The Diadem is the easiest to find, though likely hard to kill; they suspect there's only one more. (Intentionally made, at least.) Fay dives deep into the lore on the Deathly Hallows - what little of it she can access. Communicating with her international allies becomes difficult, requires leaving Hogwarts. She strives as hard as possible, often risking herself, to seek out information on living horcruxes. On how to remove a fragment of soul without damaging the host.)
(Fay borrows the resurrection stone, sometimes. She doesn't say what she's using it for.)
(Anathema spends her birthday curled up in the Chamber of Secrets with Ellie, reading science fiction books about worlds of infinite possibilities, far away from their problems.)
They hold strong.