At this point in history, there is live theater and there are movies. Nobody would mistake the one for the other.
Movies offer unlimited special effects, but the thing about theater is that it is happening right now. You and the performers share a live intersubjective experience, one that can never again be exactly replicated.
But what if — given reasonable assumptions about where technology is going — we could one day add more elements of cinema into live theater? Suppose everyone in the audience were given a pair of glasses that would allow any magical effect to be added?
A performer on stage could appear to be twenty feet tall. Impossible flying creatures could wander through the aisles. The appearance of the set could change all around the audience, in the blink of an eye. The possibilities would be limitless.
It would still be live theater. If you took off your glasses you would still see actors performing — you just wouldn’t see the added effects.
Would this lead to some sort of new hybrid form? Or, at the end of the day, would it still be theater?