the D1 was still bulky and had a fairly big bezel. A 4" screen on a GS3 type phone (basiclly bezel-less, and physical button less) would likely be the same size or smaller than a D1. And definitely much thinnerIf samsung can't promise two years of update then it will better for most users to either learn to root or get galaxy nexus for android 5.0 Os or better. Then I'm happy with my 4 inch samsung stratosphere.
To be honest I think 4 inches is to big. I like the original droid 3.7 inch not 4.6 or 4.5 inch devices. Their to huge in my opinion.
Samsung galaxy s3 will probably be from 4.8 inches to 5.