Is it possible to switch to CX for SFO-SIN and keep MI for SIN-TRV?
 

I feel a bit worried that my flight on 28NOV from SIN-SFO via ICN is gonna be cancelled. Is it possible to switch to CX for SFO-SIN and keep MI for SIN-TRV?

First of all, what airline are you flying? If I'm not wrong, OZ / KE / SQ are the only ones that fly your particular routing.

If you're flying SQ, according to the Star Alliance Reference Guide, they are required to put you on the next available flight in this order:

1. Own airline
2. *A airline
3. Other airline

BTW, what does this have to do with CX? I highly doubt that your ticket is endorsable to other airlines if you want to rebook on your own.

I don't see any particular reason why SQ16 has to be cancelled on 28NOV? Its still open for sales.