Rumors abound in regards to Windows Mobile 7, HTC's HD2, and Microsoft's purported Chassis 1. Speculation stems from the story that Microsoft has a "reference chassis" for Windows Mobile 7, and the fact that the HD2 is the only device which qualifies based on the rumored hardware requirements.
The latest round of conjecture is based on an XDA post detailing the response that he received when he asked HTC about Windows Mobile 7 for his HD2. The core of HTC's response is as follows.
"What we do it ROM Upgrades from our website, however 6.5 windows mobile has only been out 2 months and windows mobile 7 hasn't even been developed. This wont be out until next november at the earliest. But when it is available it will be a free download."
Overlooking the underwhelming English skills, let's break this down. First of all, HTC does indeed release ROM updates from their website. Windows Mobile 6.5 was released in October, so this is more or less true. The statement that Windows Mobile 7 has not been developed is probably not true, but we can be fairly certain that it is not a finished product at this point. The statement about November is very noncommittal, and doesn't seem to come from anyone with actual knowledge of the timeline. The final statement, that it will be a free download once it is released, is simply in line with HTC offering free updates for their devices. While you could read into the response and take out that HTC is committed to bringing Windows Mobile 7 to the HD2, the response doesn't actually say that in so many words.
My personal prediction is that the HD2 will get Windows Mobile 7, at least unofficially. Until Microsoft shows Windows Mobile 7 to the world, speculation about what devices will get the upgrade is simply speculation. Stay tuned for news out of Mobile World Congress next month.