robotic gear for Venus (discussion)

An interview about the history and results of the Venera Mission got
me thinking: why is no one actually trying to build state-of-the-art
"oven-ware" electronics and electromechanic components? 
While
Ferrites and Nickel are out of question when designing magnetics for
500°C, we might be getting somewhere with InAlN/GaN transistors (DOI:
10.1109/TDMR.2010.2072507 "InAlN/GaN HEMTs have been operated up to
900°C for 50 h") or even diamond transistors (DOI: 10.1038/srep06395 ,
10.1109/LED.2013.2271377) in the active department.
A 21st century venus rover? Count me in!