There is no official word if they plan on replacing those two models with new models, or if they are gettting out of the Tablet PC business altogether.
The C310 and C200 will be available through channel providers while stock lasts.
Update: I just got this in from Linda at TabletPC2.com:
As of a few months ago according to Acer they were no longer going to
selling Tablet PCs in the United States. My information came directly
from two contacts at Acer, But you never know this could change again.