Having worked closely on the circuit side of things with folks doing research on spintronics and STT-MRAM devices: it’s going to be a very long time still before this can replace embedded SRAM. The MRAM itself can be made quite small, but you still need an access transistor and wrote currents are still too high, which means very big transistors, which then dominate memory area… Also, writing is much slower compared to SRAM.

It’s a very nice embedded flash replacement though…

It might be SOT-MRAM over STT-MRAM. I'm of the impression that SOT-MRAM doesn't have the slow write problem.

What happens if i put a magnet nearby ? Does it still work ?

I have high hopes for spintronics on the power efficiency front, but for miniaturization, they are as much of a hassle as any other magnetic technology.