Well as said, it's purely conceptual at this point in time - we're really just brainstorming new ideas for monitors because having five shields like in the 2010 demo (Shield, Golden Shield, Elementals) seems redundant, especially when there are also other means of protective power-up like the ring preserving Blue-Ring powerup from Chaotix.
And Sonic would lose it, I imagine, by losing the spikeballs to certain obstacles and/or enemies, as any enemy that collides with a spikeball would result in the destruction of both. However, there could also be a sort of time release system in which every minute or so, one of the balls releases of its own accord just like an Orbinaut, though its all up in the air. Some badniks would probably be immune to the spikeballs too - in the original Sonic Zero, there was a variety of badniks equipped with Lightning Shields, and if I recall, in Sonic 3 a Lightning Shield would simply dissolve spikeballs, though don't quote me on that.
But yeah, nothing set in stone. Better than the average shield, but still with its ups and downs.