Steve Jobs has not talked to any of us so we are only guessing, but I just have a hard time believing that the first generation CDMA iPhone will do all those things. Eventually, but not tomorrow. Remember that there is going to be a push to include LTE in this phone as well which will further complicate things.
I think your best solution right now is a Global Android phone such as the Droid Pro. As was discussed elsewhere on this forum, Verizon has an International Data package for $64.99 that will extend your data package to France. If Orange is the only provider in the area, you'll still be covered. Keep your basic French phone and use Android phone for voice/data in the US and data in France. Given the high price of data in France, you may not be paying more than France Telecom would charge you for a comparable amout of data.
Now let me suggest a few additional things. Buy an account with siptraffic, they offer VOIP that will connect to a French Mobile on Orange for less than US$5 a minute. Get a cheap US VOIP phone number and a free account with pbxes.com, voxalot, or the equivalent. Program your new US number to ring to your French mobile.
Now get a Google Voice account, register your US cellphone number and your Virtual US number to the account and give your Google Voice number out as your global contact number. When you jump on a plane, forward your Google Voice number to your virtual number and receive (and make calls) in France for US$0.04 a minute.
How do you make them? By using the callback module built into a million Google Voice clients.