So I did a bit of digging back to 2014 and 2015. Here's a few posts from a few regular members
May 2014.
Tbone: minimum 4m - max 8m. This kind of prediction from his wasn't seen as unusual and was actually more generous then many posters gave it. The ps4 has now passed that 8m max and will go a good bit higher.
http://gamrconnect.vgchartz.com/post.php?id=6336857
Eric Fabian thought it was delusional to think the ps4 would sell like the ps3. Not so delusional after all since ps4 is 600k above ps3 aligned and will easily beat it to 9m aligned.
http://gamrconnect.vgchartz.com/post.php?id=6337031
Kupo thought the ps4 doomed to fail and the Wii U would stay ahead.
http://gamrconnect.vgchartz.com/post.php?id=6337107
Nintendopie found it awkward the faith some had in the ps4.
http://gamrconnect.vgchartz.com/post.php?id=6337202
The above are from 1 thread in May 2014. That summer stuck with me because the amount of posters who were not playstation fans that constantly doubted the potential of the ps4. All because of a slow start. It was 10 times worse on neogaf however then here.
I'm going to post this now while I look for more threads from that era.