It looks like there are various DSH concepts, depending on a staying duration of 180 or 500 days. The simple ones have a Unity or MPLM module plus a utility module with solar arrays. Others combine more ISS-type modules, some include inflatable modules.
Some guesses, any of them may be wrong:
- The DSH will not be built before the end of the ISS (2026). There may be a 10 years gap between these two vessels.
- The habitat modules will be of ISS-derived design, so their shape will be familiar. Extra radiation protection may be added to the interior for operation outside of the van Allen belt.
- Given the current political situation the Russians may go their own way, so maybe no Russian modules will be included.
- The DSH shall be versatile and can be relocated. The inital push will be by an EUS towards high Earth orbit, EML1-point or lunar orbit. A solar electric space tug may be added as a test bed for later Mars missions.