For isolationists and zombie-apocalypse fanboys, the future of architecture may mean buildings will resemble designer-fortresses, like The Safe House by Polish Architectural firm, KWK Promes. Impenetrable blocks of concrete plug up the windows, steel shutters come slamming down over the glass front door and a drawbridge entrance is hoisted up — and all this with the push of a single button.   To conservationists and green-libertarians, structures yet to come may take engineering cues from nature, like The Green School complex in Bali, Indonesia. Bamboo chalkboards, compost-toilets, cotton tents deployed to keep classrooms cool and water-vortexes that produce 8,000 watts of electricity, day and night, help to keep the complex off the grid.