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Authoritarian party stay resilient because they're cohesive. These are signs the PAP juggernaut is fraying, slowly but surely. https://www.channelnewsasia.com/news/singapore/heng-swee-keat-dpm-4g-leader-step-aside-pap-pm-lee-accepts-14581784#.YG7d3yc6etM.twitter
Less than a year ago, the party stood behind it's leader. https://www.todayonline.com/singapore/paps-4g-leaders-back-heng-swee-keat-leader-absolute-unity-vivian-balakrishnan
And two years ago https://www.straitstimes.com/politics/heng-picked-as-4g-leader-with-chan-as-deputy
And Milan Svolik's book, chapter 6. https://www.cambridge.org/core/books/politics-of-authoritarian-rule/7F78A8828A5714F0BE74E44A90A44868
And now party elite appear to be caught off guard and unable torally behind a leader (yet). https://www.todayonline.com/singapore/4g-leaders-say-dpm-hengs-decision-setback-succession-planning-need-more-time-choose-new
Exciting times for Singapore political science. 
A post from party colleague and speaker of parliament. Reads like a political obituary even though HSK remains in the cabinet as Finance Minister.
I stand corrected, HSK steps down as Finance Minister in 2 weeks.
Authoritarian political parties are resilient becoz it has institutionalized channels for cadres to advance careers within a stable system of patronage; creates a quasi-constitutional form of power transfer, institutionalizing & regulating succession (Jennifer Gandhi 2008)
Even if intra-party rules are informal, they offer guidelines for party elite, curbing conflict & minimizing potentially destabilizing power struggles.
Failure to these intra-party rules and SOPs, to steer a transition from one leader to another, could cause regimes to fragment and eventually fall apart (Natasha Ezrow and Erica Frantz 2011).
