I get what you mean in that he hasn't had a major hit in the time span that you've mentioned (LR could have been a hit but Thongent kind of messed that one up
). But imo Na is still very popular; if he wasn't he would not have been chosen by big companies like OPPO and PM Group to be a presenter for their products, nor would he have been able to show results for them. These kind of companies don't just choose anyone, so they wouldn't choose someone who was no longer popular. I think the scale/type of endorsements is one of the good indicators of popularity cuz yeah sure one can get lots more endorsements but if they are for small brand stuff, it's not really saying much. I don't think Na has done endorsements for small brand stuff in a looooong time, it's always big brands and big names. He's essentially the only actor of his generation that has managed to stay relevant/at the top for this long since his debut and if many are still using him as a benchmark for others, I would say he's still doing pretty well
Pope has had more hits than just BPSW and his level of fame when BPSW was
on air was pretty much the same level as basically Na's fame during the first 6/7 years of his (Na's) career lolol; rn it's more of a question of whether Pope will fade out or not. Pope is the current "it" guy (well you could kinda say Film from Mia 2018 is as well) so it makes sense that there is hype for him but I don't think his fees for events or endorsements come even close to Na's fees - and again, someone's fees is basically proportional to their popularity.
I personally think that Na only really needs a solid social media platform if he is planning on being an ambassador or whatever for something as big as LV but even then he has a specific fashion sense
so he will only agree to a brand that fits well with him & that he feels comfortable with. I don't think Na is going to change though (in terms of being private etc)
He just finds other ways to interact with his fans e.g. merits, fanmeets, speaking to them outside events or the airport.
(Soz for the long ass reply
)