The attribute "id" is already live in all production Wikipedia systems. It allows to link to individual equation that have the id attribute set.

For example the code

<math id="MassEnergyEquivalence">E=mc^2</math>

can be accessed via appending #MassEnergyEquivalence to the Page URL.

Visually no difference can be seen in the output

E=mc2

See for example kinetic Energy