I 100% understood that, which was in fact the background of my thesis: it looks like they are going to be forced ("relegated", even) to maintain old.reddit.com forever because, explicitly, so many people aren't upgrading and the new design isn't succeeding in motivating these people to upgrade (even years later!). I mean, someone else on this thread noted that the new design seems to only have twice as many page views as the new design?! LOL