Except that Madonna was 5 years into her career when that happened.

it's not about luck. She doesn't flop for a reason, and your faves flop for a reason too

I Always said that no one would've ever dethroned Madonna

true

Madonna is a legend because
a) she was the biggest femaler star in the world and the second biggest star after MJ in the 1980s
b) she was not dominant throughout all the 90s but was still very successful in some parts of it.
c) she was still releasing albums in the 2000s which despite not being smashes still had hits now and again
d) she still can have a monster tour in 2010s, this shows her popularity has endured displaying amazing longevity in her career going into her 4th decade

So it is possible that other females might also emulate that in some way - Beyonce, Taylor maybe, but even if that happens Madonna will still be lauded and remembered because she did it first.

Madonna isn't really called the Queen of Pop, it's just a nickname that is sometimes used.

Michael Jackson was referred to the King of Pop, Rock and Soul by his friend Elizabeth Taylor during a speech in 1989. In 1991, Michael Jackson released the Black or White video and made it a condition for MTV and other media to call him the King of Pop if they wanted to show the video. He wanted a 'title' like Bruce Springsteen is called 'The Boss'. As he became referred to as The King of Pop, the media then eventually started referring to Madonna as the Queen, as she was like the biggest female star of the 1980s. AFAIK Madonna did not prompt this in the same way MJ did for the King of Pop, it was just a consequence of that.

No one is touching Madonna. Especially in the digital era where is harder to sell albums.
The people having their 'kiis' at Britney should just stop.
She was a major force before her breakdown, probably the only one who came close to pop royalty status.
Gaga made a splash at the beginning but the ARTPOP era shows she's just in every other pop girl level now.
And the Rihanna mention she's super consistent but she never even reached Gaga's level at her peak.
The current pop girls can become pop icons, trendsetters and legends eventually but Madonna is the only true Queen Of Pop.

What people don't seem to understand is that 'Queen of Pop' isn't a 'title' for Madonna, it's a nickname.

People started calling Madonna 'Queen of Pop' back in the '80s not only because of her success (as the most successful female artist ever), but also because of her attitude, which was often seen as haughty or egotistical. See: Smash Hits starting the whole Madge/Her Madgesty thing in the mid-'80s.

For that reason, I (and a lot of people in the media/public) associate 'Queen of Pop' with Madonna as much as I associate 'Material Girl' and 'Boy Toy' with her.

The younger popstars and their fans don't seem to be in on the joke, but she most certainly is.

When did Britney come closer to Madonna ?

Britney was a teen idol in the 00s, same case as BSB or Nsync...and 1D and Justin Bieber nowadays! you wont find anyone in this world who would compare BSB or Nsync to the Beatles or the Rolling Stones

Lady Gaga came closer with The Fame/The Fame Monster era but seems not to have longevity, we will see.