It’s not currently possible, but this is certainly something we’ve been considering for a while. Some discussion around this issues in various places, e.g. here or here. One of the issues we’re discussing is what format to use for this, given that we’d likely need to pass not just streamlines vertices, but also per-streamline weights and potentially other information too. We’ll do it when we find the time…
This line is basically identical to the pipe you suggested, in the sense that tckedit outputs a temporary file, which is then read by tckstats and cleaned up at the end. The main difference is that the temporary file is given an explicit name (tmp.tck in this case), which forces it to use the .tck file format.
P.S.: Using the && operators ensure that the subsequent commands are only executed if the previous commands were successful (i.e, returned without error).