It is quite clear that we don't know when we will get hold of Dolphin 8. What i would like to know is whether it will be possible to upgrade from D7 to D8. This makes sense for those who might be seriously developing their D7 sites.
Depends on how you define "upgrade". Automated upgrade script from D7 to D8 - not going to happen. Tools for migrating compatible data - sure. Compatibility with current D7 expansions - somewhat. Generally, we recommend working with D7, especially now that 7.1 is in works, and only -consider- D8 when it's out and if it fits your site's objectives.
Keep up the good work.