There's no doubt IPv4 WILL still be here in a couple of decades.. but that doesn't mean that the majority of networks will still be using it..
The fact is, more and more mobile networks are making the switch to IPv6 NOW.. and that's causing compatibility issues with the default FTP uploader...
Since the FTP v6 uploader is backward compatible with IPv4 anyway, what's the point in keeping the old FTP uploader?
It's like people arguing against BluRay media because DVD's will still be around in 10 years, when you can play DVDs on a BluRay player but not DVDs.