In MMIC, LMDS and MMDS both went nowhere. Auto Collision Radar has been in the works for years. They are working on 60GHz CMOS and SiGe Wireless LANs.
Is this all necessary ? What COMMERCIAL applications will drive both RFIC and MMIC design in the future ? Which technology will win out ? SiGe ? 90nm CMOS ? GaAs ? InP ?
Technologies always generate or re-invente new applications.
One of the exciting technologies today is, I'd say, WPAN and wireless sensor networks. Look at the (overhyped) Bluetooth, WLAN's and (to become overhyped) Zigbee RFIC activities. I'd admit that I am sucked by the Zigbee wave, but the finale future of this tech is debatable.