I'm confused now. If they need 10 million, why are they not asking for that amount, why doesn't it say that on the kickstarter, and why is it not listed as a stretch goal?
Here's how Kickstarter works.
Developers in the past who have asked for the realistic number hardly make it. Even if you're off by a dollar, the game would not be funded and no monies will be given to the developer. Once the goal is reached, the real game begins (which is Stretch Goal). These are the elements that will make the game bigger and better and more accessible, like more mini games, more playable characters, more events and scenarios, and even announcing support for hardware like Xbox One or Wii U.
In this case (which is now a norm in Kickstarter), developers will ask for money that will ensure that a minimum viable product can be released. For 2 million, we will finally get Shenmue 3. It may not be how you remember or expect it, but the elements will be there and story and gameplay would be there. To get a good Shenmue experience, they need a lot more money (A LOT).
$10 Million is the suggested cost to squeeze the most out of the Shenmue universe. They are slowly revealing stretch goals, and no one wants to say "$10 million is all we need" because that isn't true. There's always money needed to push the game from an indie title to AAA title. Maybe they're hoping they get way more than $10 million. They may add even more stretch goals after $10 million.
For now, it seems a good enough number to comfortably release a decent game without looking like chumps.
TL;DR: THE Shenmue III will cost $50 Million.