RMAF have 2 RF-5E plus 14 F-5E/F.
They going to sell off 7 of them, so it make 2 RF-5E and upgrade 7
F-5s.
The qn is what kind of upgrade?
Currently most F-5 upgrade are avionics and radar, and most nations
like Turkey, Brazil,Chile etc are going for Israel's
Elbit/Singapore's ST option.
RMAF will never take up this option. Their loss.
Then there is Northrop-Grumman option(F-20?),not sure any nation
have taken up this, maybe it cost more than Israel/Singapore
option.
Next qn is why only 7?
7 F-5s is only 1/3 of a full sqn, unless they are not upgrading
them as fighters.
I suspect they are going to be converted to RF-5 recon a/c , in
view of the small number.
Singapore ST has converted some to RF-5s for RSAF as well as for
Taiwanese AF, most likely RMAF will not go for this option as
well.
Then they have to go for the more expensive route by having them
converted by the US's Northrop-Grumman. 
My 2 cents worth.
