It will be nice to have zero inductance, but that can not happen yet.
A fair price is about the cost of a Exodus Tempest X2 or a few US dollars than that.
One thing that will be nice is the efficiency be at least 88 dB. Sure you stated that the SDX15 Mark II can handle 2000 watts, but that does not mean anything to me. A lot of high Xmax woofers from your competitors have low efficiency. Your TRIO12, TRIO8, and SDX10 have an efficiency of 85 dB which is low efficiency. I am willing to spend the money on efficiency compared to spending the money on a marketing tactic that bases on wattage handling.
Another thing that will be nice is a dual 4 ohm voice coil version to provide more choices for hook up. A dual 2 ohm voice coil version is OK, but has the fewest choices for hook up. A dual 4 ohm version can be hooked up in series to provide an 8 ohm to benefit to hooking up two for an amplifier that is 4 ohm stable or up to four for a amplifier that is 2 ohm stable.
First off, i'd like to say that the power handling isn't a marketing ploy, its moving up one of the very few limitations of the old driver. Secondly i'd like to say that the SDX 15 Mk II is aimed at home theater, which is why you see the voice coil configs that you do. And Last, I'm curious as to if you've seen anything with similar xmax in the 15" category that has a sensitivity higher than the SDX 15.
For what its worth, I think if Bob can keep that same amount of Sensitivity with the higher xmax, we will all be happy.