We don't know*
I suspect - despite our, and the communities, best efforts - there will be some hack-ish workarounds for defects in v1.0. Part of v2.0 would be addressing these issues, and we need some time to pass for them to become obvious.
Another part of v2.0 would be bringing the API into line with the improvements made on the sites. The longer we wait, the more we can knock out in one go. Of course, the longer we wait the longer [app]s don't have access to things displayed on the sites. Something of a balancing act there.
Finally, since we've implied - though not quite promised - write access in v2.0 the exact mechanisms for that need to be worked out. This implies significant UI changes, in addition to some serious platform work. The price of failure with regards to security is also very high. A lot of internal work will have to be done to even make v2.0 possible before we start bringing in the community to work on the public aspects.