MAS has a very strict upgrading policy which has its bad and good but being too strict (like MH
's policy) is on the whole not too good for her loyal passengers IMHO.
MAS wouldn't even upgrade their Enrich Gold members (even those top on the list that have had the Gold status since the Passage days) to F but rather leave that entire cabin empty while these frequent C class flyers remain in C class. There is nothing much employees can do because this is company policy.
I believe SQ
has a similar policy. Myself I prefer if they were a tad bit more flexible, not necessarily upgrading en masse, but just pick out a handful on a flight especially when cabins are sparse, esp J to F and to a lesser extent, Y to J.
So answer is that your chances are slim unless an overbooking situation exists at time of your flight of which then they will upgrade passengers to make sure all seats go out filled.