sortMode has no sence now at all as there is no built-in sorting at the table. (used only with JS API now instead of isClear parameter - but why we need two ways for the same?)
If we will create out-of-the-box functionality for sorting and will add some behaviors for doing sorting/filtering(instead of built in to table as in 3.3.x) - we could add something like isResetSorting flag to the control itself.
I'm not 100% sure on that. So want to discuss.