Have to admit I don't really get the rationale behind the brakes on the trike. Granted it won't fall over as easy if you lock a wheel. But it does seem behind the times for such an expensive bike. And it's version of the new linked brakes is pretty lame. Hardly linked for bias control at all. More like "shared" rather than actually intelligently linked and, even then, only when using the back brake.
There will be people who hear a salesman say the trike has linked brakes who have familiarity with a Goldwing or other systems and who then will only use the rear brake. When they do they won't have a clue they're only using two pistons (and smaller pistons at that) of the six pistons in the front calipers.
As for triking an existing touring model.... I'm sure someone a lot smarter than me will develop systems for it. But it's not as easy as just removing and bolting on parts as such a chore used to be. You've now got heavily integrated systems controlling brakes and lighting that can't as easily just be split and spliced. The ECM, BCM and ABS management systems simply won't "know" what to do with the differences.