FWIW I personally won't be making any hasty transfers - I think it would be prudent to just let the dust settle and assess all scenarios.
I do think Citi will at some point not too far down the track reinstigate these changes to the conversion rates - but they will indeed be giving the required 90 notice.
This will give all of us plenty to time to fully investigate 'best usage' of Citi rewards. Personally I might shunt to several FF programs rather than all to SQ.
Might I suggest that ALL Singapore Airlines KrisFlyer members send off an email to SQ regarding the 3 year expiration period for points. SQ are quite out of date here - probably the only major top tier carrier who still have this archaic system in place. Who knows - people power brought sufficient pressure to Citi to change their minds - a whole bundle of emails to SQ feedback might possibly bring sufficient pressure also.
SQ feedback email address here -
[email protected] - SQ might already be considering this to bring themselves into 21st century - or they may never change - but in last few days we have all witnessed the power of the people!