A quick up date. I started to improve rapidly about 5 days ago and feel pretty good. The dizziness from the concussion is less. The numbness in my left arm and hand is also resolving. Both of these injuries take a long time to resolve, I am being told, so it could be months before I know if they are permanent. But for now I feel a lot better.
I have had a chance to look at my bike and it is definitely dead. The rear dropouts were torn out of the frame and broken. And one of the seat stays is crushed--I can squeeze it with my hand.
Thanks for all the best wishes. And for my wife and daughter who took great care of me for the first three weeks when I was pretty much out of it.