I don't think the value of the pre-'64 rifles has changed much. They're still the same as they were before the new guns came out. And they're getting more worn and dented and dinged as time wears on. Many are used in custom builds - we all know the value of custom rifles is in the eye of the builder, those receivers are essentially apart of something else once they get smithed like that. So the number of actual, good condition pre-'64's is going down slowly but surely, ensuring the rest of them will hold their value for a long, long time.
That being said, the new Model 70's are f@cking fantastic for the price and represent a tremendous value for people who appreciate blued steel and wood instead of plastics. Sporter, Featherweight, Super Grade, Safari Express, all of them are great. All-weather guns are a dime a dozen nowadays (okay maybe not) but Winchesters are just as good as anyone else's in that price range as well.