I've got the G2 & the F100. Both very different and unique cameras. I've used the G2 for studio flash with good results, but G2 on-camera flash forced me to select the Nikon F100. I now carry both cameras. For travel and scenics .. hard to beat a G2 with Zeiss glass.. I just love that camera. The F100 is used for serious portrait work, outdoor fill flash, etc. Nikon flash is definitely a superior system -- and with portraits, do you really want Zeiss sharpness and contrast?? Sometimes I do, but mostly I don't.
The F80 is a great camera, but my choice was to go with the F100 because I can use 1/3 stops for slide work. Keep your F80 - it is damn near a perfect camera.
I stressed a little bit over getting the F100 when the G2 seemed to be just so perfect in almost all shooting situations. So much so that I almost bought another G2 over the Nikon.
As for "orphaned systems" -- here's my take: All modern cameras have built in obsolescene. The more modern and computerized the camera, the greater the risk. Remember, those LCD's - well they have a limited lifespan and when they go, that modern marvel will be dead, and 10 years plus will mean parts are hard to find. If I was a camera "seller" I'd push you into every new technology available.. yes every two years I'd be telling you to upgrade, change cameras, promising you ever better results .. what nonsense!
Remember, why you want a G2 .. small, light weight, superior optics, relatively ease of use. It is just a damn fine camera. I consider it a camera for a discriminating photographer because while it limits shooting scenarios .. when used for what it is designed .. it is absolutely superior.
Keep your F80 .. but get the G2 - enjoy it for 10 years (that's really less than $100 a year to own it) and shoot lots of film -- this camera is a hands-down winner that is better than the photographer in many situations. I drool over my night shots of outdoor urban scenics all decorated with Christmas lights (downtown St. Louis)... taken with the G2 on a tripod .. during the coldest day of the year .. at 2AM .. no people ... just wonderful buildings and Christmas lights .. with the G2, I felt I had achieved the best photography I've ever done .. better than many of the postcards I'd seen taken of similar scenes. I've owned this G2 for a little over a year .. and I'm learning to appreciate this tool for what is was designed. If I broke it or lost it, I'd get another ... obsolescene be damned.
Marketplace?? I don't care about that, a camera is just a tool. I don't care what everybody else shoots .. hell, I hope they all go digital .. for me, I intend to take pictures, not buy/sell cameras, not spend hours tweeking photos on the computer .. (if that's your thing.. enjoy it).
But, that's me.. I still use my old Canon F1's, all three of them .. drive an older model Chevy Impala SS ... cause I like that Corvette engine .. and chase women over 35 .. becuase I like an experienced girl -- new models don't impress me much. (What was the question again??)