Two suggestions:
Have an extensive private beta with lots of folks from these boards, and don't release it until it is feature parity with the existing online system.
This is pretty much the plan, actually. We already have the invite list for the first round, which we hope to start within a week. Then we'll post to open it up to people in these kinds of forums. Then eventually we'll make it a public beta and announce it on the site.
Feature parity is approximately the goal (although that's quite a big deal!) It's certainly true that our mission is to migrate onto a system that we can actually maintain and improve, rather than focusing on new features. That said, there is no point in re-implementing some of the bad stuff. For example, people want to generate kingdoms like the millions of Dominion picker phone apps out there do; they don't want to do it like Deck Builder. Another example is the awful room/table metaphor that was copied from the first version of the Internet Gaming Zone in 90's. So, if the launch is temporarily missing stuff, it will be because we're in the process of replacing it with something entirely new and better.
Especially with how badly the original Goko rolled out, profitable Online Dominion probably really can't survive another botched launch.
I think we agree, but it's a little bit apples-and-oranges. Goko wasn't trying to launch a game; it was trying launch a system for game developers to make their games in. Dominion Online happened to be one of the sample games. Contrast this to Making Fun, which actually is a game developer/publisher, and where the players are actually the customers.
Keep the existing Online Dominion up even after the new one is released. Let players "vote with their feet" to move over to the new system once they think it is better. If nobody is moving, then the new implementation isn't ready yet. Shutting down the current one prematurely would likely annoy current customers, and it is the current customers that are going to help spread the word of a new mobile release.
We will have both running side-by-side, initially with purchases only allowed on the version 1 system and migrated to the version 2 system. This won't last forever though, because the version 1 system is too expensive to run.