It is more F-15s AND F-35s! The decision to shift PLAB already
funds both acquisitions. The F-15SE is not as stealthy as the F-35
so the incremental benefit compared to the F-15SG may not justify
the added cost i.e. F-15SG almost as effective. AFM july 2013 issue
already reports Singapore has ordered another sqn of F-15SG as
F-15SE & F-35 not ready yet. In any case, many of the F-15SE
features e.g. CWB can be retrofitted on F-15SG.
If just more F-15SEs are bought, Singapore will need more
airbases as each F-15 needs minimum 8000 ft runway.This has to be
funded by tax increases as PLAB cannot be spared. Saudi spent $30
billion for 84 F-15SA (not even -SE) so that's a lot of taxes to
raise.
On the F-35, recent reports indicate 75 will be bought which
presumably will replace the F-16s. In selecting the F-35B variant,
this allows the RSAF to buy more fighters in exchange for PLAB land
sales. The F-35B can take off in under 600 ft of runway without ski
jump and no need runway to land so more aircraft can be based per
runway! Recent land sales data show each hectare can fetch as much
as S$300m or more for Paya Lebar area (todays prices not even
counting future inflation). In 2030, the land price could be even
higher. PLAB = 800 hectares.