As a regular traveller from CGK, I can tell you the number of connecting passengers is huge. QF only serves SYD from CGK and, even then, not daily. When I check in on 3K204, which I do quite often, there are a significant number of passengers who are connecting onto evening services from SIN on QF, EK, KL which are all codeshared on the service. The same applies on 3K205 from SIN which connects those arriving into SIN during the late afternoon bank of services for a 9PM arrival into CGK.
So one flight is the evidence that the whole operation "relies more than ever on connecting passengers "? That was my point - that it's a very small number of flights that are even viable, so hardly that the operation is reliant on it.
At present 3K have two daily SIN-CGK. Only one presents any realistic possibility of a feed from QF, JQ, EK and KL. The second flight is 3K201, a 7:50am departure from SIN. There are no QF, JQ, EK or KL early morning arrivals in SIN at present. They are all late afternoon and early evening arrivals into SIN. Do people overnight for a connection. Small numbers may, likely very low yield and hardly reliant given alternatives.
The same scheduling challenges exist for most/all other routes, and even worse on a lot of routes. Take DPS as an example. 3K also have two daily departures. Morning departure has the same challenge as CGK. Afternoon departure is 3:50pm, so too early for most connections. Only EK can make it with a 50 minute connection.
Let's look at KUL, their biggest route at present with three daily departures. First two are too early for any connections. Only the third is possible. BKK, HKT and MNL: two flights, morning and early evening (most still less than daily for some or both flights, so limited flights that can make connections). Morning is not possible, evening possible. PNH and PEN are afternoon and evening. But same problem. In this case, frequency is only about 3x week combined. CRK is haphazard - no connections possible. SUB morning only - no connections possible.
So we're looking at one flight to CGK and KUL, and a very limited hodgepodge to others. Probably looking at only a quarter to a third of flights can even make connections, nevermind being reliant on them for connecting passengers.