the longevity of amorphous metal
The answer to your question is no in general. Because amorphous metal is usually an alloy rather than a pure metal. These alloys are made of atoms of largely different sizes, which results in low free volume and higher viscosity (compared with other metal and alloys) in molten state. The viscosity hinders the atoms movement to form a crystal.

So, the significantly different atomic radii of the components that constitute the amorphous metal (about 12%) favors the high packing density and low free volume. This leads to a complex crystal units with higher potential energy and lower chance of formation. 

Accordingly, I think that even if we heat an amorphous metal above a threshold temperature  and let it cool slowly, we won't have a conventional crystalline structure. At best, we get regions of some order.