One day, Lucian will not be a top tier ADC
So other ADCs like
can become popular as ADC picks once again.
Please, I know Quinn and Varus are played Top and Mid respectively, just calm down, I'm talking about ADC here
Edit: Wanted to add clarifications about why Lucian not being top tier anymore would diversify the ADC meta.
Well, simply because he's basically the ADC of S4 Renekton.
Remember S4 Renekton? Yeah, him. The croc that literally decided what was meta and what wasn't? If a champion couldn't beat Renekton in lane, it was trash tier, which is why only few picks were still viable (
)
Well, it's practically the same with Lucian right now.
Every viable ADC has to beat Lucian in order to actually be viable. Hence why the most popular ADC picks right now are

Ezreal is so safe, Lucian can never kill him, Caitlyn is also mega safe and has the range advantage over Lucian, Jhin is just Jhin and one shots anyone within 4 AAs, Jinx is a little overtuned now (tho she has received some nerfs, so let's see how it plays out)
But right now, unless you are a devoted one trick pony of that champion, there is just no reason to NOT pick Lucian instead of the ADCs mentionned above. I mean, sure, they fill their niche, but there is no reason to pick them, when Lucian can also do their job, and be an overall more safe pick.
Which is why when Lucian wasn't top tier anymore, other ADCs were viable. Remember Pre-S5, when he was literally LOSECIAN? Aside from Vayne in every single fucking game (but she was practically permabanned, so meh), there was a HUGE diversity in the bot lane, as every ADC could be picked without worrying about if they're trash or not.
,
, and
will never be seen at worlds. Until 2030, I won't hold my breath though!