If by chance the Navy did decide to upgrade:
They have a 45 foot beam; could an aegis system be built onto that narrow a platform?
I have no idea, but it wouldn’t be needed. Frigates would be used for anti-drug, anti-piracy, and humanitarian assistance operations, which would free up the more powerful warships for the jobs they were intended for.
The Aussies upgraded their frigates to fire the SM-2 from the MK-13 launcher, in addition to installing an eight-cell MK 41 VLS for the ESSM.
http://www.defence.gov.au/Publications/NewsPapers/Navy/editions/5301/5301.pdf
http://www.nepeannaval.org.au/Museum/Frigates/Adelaide-Class-Frigates.html
There are some interesting Israeli, European and Australian radar systems that would be light enough for a frigate like this.