I might be really dumb, but you get 3 stacks of Harnessed Shadows and then use TK Throw which grants Shadow Protection stacks? That's what it sounds like but the "it" threw me off a bit.
Overall I would be sad if the self-healing nature of this spec is removed to the degree of these changes. I imagine there has to be a workable middle ground.
The way I read it, it sounded like instead of Harnessed Shadows, you get Shadow Protection instead and TK throw will no longer be part of the rotation, although I could be mistaken. I'd prefer it that way anyhow though as TK throw/Force Lightning doesn't really seem like an ability a tank would use anyways.
If it works the way you described, that would be a bit awkward, as it would require that a Shadow MUST get up a 3 stack TK throw every 18 seconds in order to maintain a 4% damage reduction throughout a fight, and if it falls off it would take them over a minute to get back up to 4% again, none of the other tanks have such a strict requirement on their attack-activated buffs.