I don't accept your premises.
"Create a version in Flash and not support the iPhone, iPad, and several other phones."
When the Flash 10 Player is officially released, mobile phone support shouldn't be an issue, except for Apple devices. So do you re-do everything, or start new with a new HTML 5 spec, to add support for Apple Hardware? Or do you use Flash which covers pretty much all devices and let Apple users miss the experience? So 15% of the phone market misses out...is that really that big a deal? Maybe...
"Create a version in Flash and a version in HTML5 to support both regular Web browsers and the iPhone, iPad, and Mobile devices that don't do Flash?"
Surely not ideal, agreed.
"Just create an HTML5 version without Flash, and still support both all major browsers and the iPhone, iPad, and other mobile browsers, excluding some very old versions of browsers that have not installed the Google Frame plug-in?"
It's not a finalized spec, and won't be for a few more YEARS. There's no consistent browser support. A killer to much online video, there's no DRM (as 'evil' as it may be). There are no IDE tools to support the animation components (though Adobe will be the first to release one).
Finally, the Flash Player needs work, no doubt. Flash itself has been poorly used and written by many, no doubt (not Adobe/Flash's fault). So browsers which will now render all this stuff natively...won't be bloated, won't eat lots of RAM, won't be slow...