Heng Swee Keat is rumoured to be the PM-designate, the most likely to succeed PM Lee.
If true, his aneurysm and stroke is most untimely. Yes, there is a chance that he might make a full recovery. But there is also a chance, a better than fair chance, that he might not.
If so, the PAP's succession planning has been thrown a curve ball. Maybe not into disarray, because like all good plans, there are back-ups, stand-ins, and contingency plans.
There are at least three alternates who can step up if Minister Heng does not make a full recovery (or enough of a recovery) to take over in a few years time. Likely PM Lee will want to hand over leadership in the mid-term (in about 2 to 3 years time).
Also who will hold the Finance portfolio while he recovers. Or if this job is too critical for a holding position, who will take over? If someone takes over, Minister Heng will have the "honour" of serving as Finance Minister for the shortest term.
[Edit: Missed the news that Tharman will be covering the Finance portfolio in the interim. But this is presumably temporary. But it may become permanent. Which would be a bad sign.]
(I had to rephrase the above sentence. I first wrote, "Min Heng will have the 'honour' of being the shortest Finance Minister in Singapore's history" which might have been misunderstood as a jibe about his physical statute.)
Minister Heng is being treated by the National Neuroscience Institute. Professor Lee Wei Ling used to head that institute. Now she is the Senior Advisor and does not have direct operational duties (I assume). And recently she accused her brother of abusing his power.
Might make for some awkwardness if they bump into each other in TTSH.
And in case anyone is wondering (I'm looking at you, Chee), there probably will not be a by-election in Tampines GRC.
However, speculation about Tharman being PM as a stop-gap measure (to allow newer ministers get enough experience to take over as PM) may arise again.
Or (more likely) PM Lee will have to continue a little longer than he intended.
This is a major blow to the PAP's leadership. It's a bigger deal than if SDP had won the Bukit Batok by-election.