We are waiting for Microsoft's plan as well. WinPhone7 is definitely not a business fit for our customers yet we have not heard what the plan is for WinMobile. To date we have treated the WinPhone7 as a fork and patiently wait to hear the news regarding
the other prong.
In the Q&A after the first Windows phone session by Charlie Kindle, they talked about not providing new features for WindowsMobile just supporting what's there. So I guess the other branch of the fork will be something else. Some day.