This depends a lot on whether or not Verizon gets a version of the One in the near term. The Butterfly and DNA are different enough in hardware and kernel that, much like the different between a GSM Nexus and Verizon Nexus, it may be 1. More difficult and time consuming to make the update and 2. Difficult to get Verizon to support it and push it out. If Verizon decides to truly treat this as a flagship device and does not release a subsequent HTC hero device within the next 6 months or so, the chances are better of getting it sooner, if at all. If they do release subsequent, I'd assume that the line about "some Sense 5 features" may be more applicable. The Thunderbolt and Rezound are also similar to this concept, in that both got screwed by the presence of the other and the Rezound got releases, but they were buggy and had support issues from day 1, while Thunderbolt owners felt like we were straight up abandoned by Verizon.
If upgrades are a serious issue in your satisfaction, I fully recommend the Nexus lines. Since going Nexus and having the much bigger and better MOD community I've never been happier with not being dependent on OEMs or carriers for updates.