So for the sales of the HD, I don't see ICS as much of a selling point. While we know the OS is greatly improved from Gingerbread, there aren't any visible standout features for the masses. With ICS, it's mostly under the hood, besides the cosmetic differences (which will be altered/hidden by Motorola's skin). There's nothing like Siri on the iPhone to market as the coolest thing around (even though Siri is actually a beta product that worked maybe half the time when I had a 4S). But there's no single thing to pull from ICS like that as a unique and completely different feature. The only way ICS will matter on the HD is if Motorola has, as you put it, an ace up their sleeve with an exclusive feature that will also be brought to the RAZR/MAXX (because if it's not being brought to the RAZR/MAXX, then holding the ICS update until after the HD again makes no sense). In that situation, I could understand holding the RAZR/MAXX ICS update until after the HD. Short of that, there's really no good reason to delay releasing it if they have a stable build that's ready for distribution.
But of course, both Motorola and Verizon constantly do things that make no sense.