To be fair, the DPJ has been dead for years. This is just confirming what has already been known. In a way, this is a good thing because the DPJ was never going to win, and they were never going to provide any real opposition to the LDP. Their going away just means that there's no longer any illusion that they would do anything worthwhile.
The real threat they see is the rising Chinese navy. China's navy will likely surpass US in next two decades, which will give them far too much power in trade negotiations and saber rattling like South East Seas.
It's going to be many decades beyond that before the PLAN is more powerful than the US Navy. A navy is the most difficult military arm to build up experience and capability in, and the US still maintains a massive advantage there.
Good thing the communists are still around!
The Japanese Communists are perhaps the only proper opposition party so you're maybe not that far from the truth. More realistically, the only likely way for Abe to get ousted is from within the LDP, and that's unlikely to happen this election (unless Japan First wins some major victories).
