So I took the plung and upgraded my Late 2013 Macbook pro from Mojave to Catalina. Everything else "seemed" okay apart from the fact that I had no wifi. The icon was greyed out. I tried all the usual advice, SMC and NVPRAM/PRAM resets. I even deleted the Network plist file but still the wifi icon was greyed out and from the System Information App all I had under Network -> Wi-Fi was:
Software Versions: CoreWLAN: 13.0 (null) CoreWLANKit: 13.0 (null) Menu Extra: 13.0 (null) System Information: 12.0 (null IO80211 Family: 12.0 (null) Diagnostics: 1.0 (null) AirPort Utility:
In the Network app, the Wifi interface isn't listed when I tried to manually create the wifi entry. In the end I was ready to take my Macbook pro for repairs as I believed that my wifi interface was fried. Then I decided to downgrade back to Mojave and it worked perfectly.
I tried the upgrade again up to Catalina and the wifi problem showed up again. So now I'm back on Mojave. The supprise for me is according to Apple model of Macbook pro is supported by Catalina so I'm not sure whats going on.