Beginning of the end ? perhaps, but it'd take several cycles of continued all-out warfare for that to happen.Do you remember the primary battle between Bush and McCain?
McCain was very much seen as an outsider and a threat to the establishment.
Or how about... Bush and Perot?
This internal squabble in the GOP is not anything new, just a more fierce battle than before. Nor does it signal the end of the GOP, but if you want to speculate that it's the beginning of the end, I won't stop you.