Unfortunately, no, I don't think those changes would do much to solve some of the underlying tank balance issues.

First, Paladin damage just isn't really a problem. They do good damage, but they never really burst particularly high, and they're a slave to multiple cooldown timers. The issues with balance re: tank damage are, basically: 1) DRK isn't performing up to scratch - low maximum damage, low average damage, optimization is the hardest among the tanks but the reward for optimizing is a fraction of what you get by optimizing the others, etc, and 2) WAR is being over-rewarded, as per usual, by having both the highest burst damage and the highest total DPS.

Second, Dark Dance was basically a useful cooldown in conjunction with the rest of DRK's 3.x toolkit. Pairing it with Foresight for 'fluff' physical mitigation is gone, using it to proc Reprisal is gone, DADD+DADP was extremely expensive MP-wise even when Blood Price was literally 4x as strong as it is now and DP cost half the MP; now it would basically be nonviable even if it were replaced exactly as-is. And wasting a DA worth of MP on Dark Mind is already generally a losing move, and that's with an actual powerful effect - tacking the same cost on to anything short of a 100% chance to parry would honestly be pretty irrelevant.