I see two things clearly here. One is the natural cycle of birth, growth, plateau and then decline/death. The other is the corrupting influence of power.
Even a political party like the PAP is not immune to this natural life cycle. When you've difficulties attracting good, talented people with a heart to serve, then your decline starts. And it's a no brainer why there're difficulties -- when there's no longer trust that you care about the people. Politics are all about people and when you can't attract new blood, you'll die soon.
Having said that, some die faster than others, from the corrupting influence of power. Power is sexy and seductive and if you're not careful, becomes addictive. You like it so much that you'll do anything and everything to hold on to it. You start to allow personal interests to influence your decision making, hurting the people along the way. You may not have the intent to hurt the people, but you're so consumed in pursuing your own political agenda that you no longer care. You become indifferent to the needs of the people. And when this happens, it will hasten the decline of a political party.
And in life, your just can't escape these two things. It will happen.
yes it comes in cycles but the fundamentals are still there. pap is losing it while wp is rising. and wp is rising because it has the image that it is like the pap of old.