Everything is regional as well. As with most cars living in the rustbelts, it's going to be hard pressed to actually use a car for what it is intended and keep the sheetmetal rust free. You find that rust-free example in Arizona or New Mexico, but you know the paint and plastic may be crispy. G-body cars had their share of weak/rust prone areas anyway, so they didn't always fare as well as their earlier siblings.
Fortunately, I live in the south where my 85 442 has never seen snow or endured weeks on end sub-zero temps. But there are many that haven't been as fortunate and have met their demise by mother nature or by accidents.
IMHO, and as much as I'd like to see it, the G-body, in general, will not garner the collectible status of many a car. Prices will rise just due to dwindling availability and still moderate demand, however, so this is a good thing for those considering buying one soon. Luckily, they made 40 zillion of them so it will take a while before the only place you see them is in a museum.
It's kind of two-fold issue to me though. Right now, you can still find project cars that are reasonable and you can still fix them up as far as you want to. Collectible status forces out more the hobbyist who likes to have car fun on the cheap. Enjoy them now while they're still able to be found.
But here's my gage on whether the G-bodies reach the "collectible" status: When the average hot-rodder who likes dropping LS engines in their cars stop doing that and rebuild that anemic 267, 307, or whatever was under the hood, instead of going for a transplant because it's worth more stock, then it has arrived. Until then, no. Prices may go up, but it won't be for collectability reasons. More of a dwindling supply with still moderately sustained demand. I might be wrong, but I never thought for a minute the G-body would ever become a collectible car in notion that people normally think about.