I'm just speculating here, but I believe this optional upgrade is intended for the Sierra-1 monitors. Now with Dave, anything is possible, but the Towers are already Ascend's flagship performer offering exceptional SQ in a 3-way design (plus optional RAAL upgrade). Meanwhile, folks have inquired about a Sierra-1 upgrade and Dave has been working on various designs.
You should be safe...for now.
Emphasis mine. I remember Dave saying that the current 70-20XR model could not be fitted to a current Sierra-1 cabinet. I have a lot of faith in Dave's ingenuity and engineering skill, but that would take a miracle to accomplish. Then again, this wouldn't be the first miracle he's pulled off.
I'm with all of you; looking forward to future announcements. As I've mentioned before, I just don't have the space for Towers. My Sierra-1 monitors are placed on Auralex MoPads resting on a computer desk. If Ascend can offer an additional upgrade for these puppies (beyond the NrT), I'm going to do everything I can to get it.
When this upgrade is ready, it will be interesting to hear Dave's feedback on the level of performance compared to the Towers. For example, this upgrade will deliver 84.93% of the NrT Tower performance (number pulled from thin air for demo purposes).
Oh, and one more thing: I'm sure we'll have to twist Curtis's arm real hard to stop by the Ascend workshop when Dave is ready for show and tell.