general relativity - Could there be any alternative to a supermassive black hole that might explain Sgr A*?

I am aware of How do we know the stars orbiting Sgr A* are orbiting a supermassive black hole and not just the center of mass of the Milky Way galaxy?, which asks why the motions of stars near the Galactic centre suggest a 4 million solar mass black hole.

But are there any theoretical ideas to explain these observations, that avoid the conclusion of a black hole, that remain unfalsified?

And will subsequent observations (e.g. with the Event Horizon telescope) be able to falsify these alternatives or indeed the hypothesis of a supermassive black hole?