The reshuffle honour loss seems like it might become a legit dishonour tactic eventually (which is good because some strange people seem to enjoy milling the other guy to death), but first and foremost I'd hazard a guess that the design intent was simply to stop games dragging on forever. Although it also fits quite nicely with the mono no aware angle (your time has passed, your clan falls by the wayside).
On dishonour itself being a reliable win condition, is it really necessary? Now that we have political and military conflicts rather than just military focused battles of force, those clans (Crane, Scorpion, whoever else) that are generally seen as masters of the court can demonstrate that by breaking provinces politically. The things those clans do to reach those goals will just look very different. Crane for example doesn't have to honour out to win, but can gain and spend honour pretty freely in order to ensure that they always have the upper hand in conflicts. Scorpion on the underhand, are presumably going to focus more on making life and decision points very hard for their opponent, and backing them into a corner before stripping them of their lands.
On the whole, this seems like a much more flavourful and interesting mechanical interpretation of honour than we ever had in Old5R.