Best answer by Julian
very interesting question you are asking here!
I once read that in 2017, more content was created on the internet than in the past 5000 years offline... That is why Google loves when things are recent. Old content might be outdated, e.g. you have different products now or the interface changed significantly. On the other hand, old content already built up quite some ranking value in terms of views and past activity. So this should not be ignored of course.
Google also loves interaction as it shows you are not just some random marketing website. So any activity (especially recent) will "push" value again in terms of SEO. This is more or less the same for both cases as far as I know. But I am not an expert in this...
I am not sure if it is possible to generalize on this, as there are many factors involved (how many views did a topic get and when, are the keywords comparable, total amount of reactions, etc.). I f we say all things are more or less equal, then I would understand it more as a process of competition of content. New content always needs to "grow" in ranking first before it has generated enough views (and also comments) to outperform and old, already high-ranking topic.
I just googled a high-performing keyword for an issue with a TomTom device, and found that older topics were still outperforming more recent content:
The topic from 2011 has more than 25000 views and 40 comments, while the topic from earlier this year has fewer comments and views. So I would guess that this will stay the same until the new topic has generated more views or comments. However that is just my take, could imagine that there are other opinions.
In any case though I would not recommend to replace old content with (same!) new content - this way you throw away the value that an old topic has built up over the years.
Hope that helps!