Like text-overflow: -o-ellipsis-lastline, or -webkit-line-clamp did. Details at http://stackoverflow.com/questions/6572330/is-it-possible-to-use-text-overflowellipsis-on-multiline-text
This is being considered, but this is a surprisingly difficult problem to solve well. The existing solutions you refer to work in some simple cases, and fall apart in the general case.
The eventual solution is expected to use the max-lines property and the continue property (possibly renamed) to define where your content should be cut, and what happens to the remaining part after the cut, and probably a (yet to be specified) pseudo element to define what gets inserted to show the ellipsis.