In terms of numbers i.e. if we conclude legendary status can be acquired via arithmetic alone, he's at 60 wins & has a current 3x winning streak in the Vuelta. Add another Vuelta next year & he'll mathematically become the most impressive performer in that GT in its history. 4x Vuelta in a row has never been done.
But then there's the battles of the particular era which mean more than numbers, i.e. the legendary fights people remember. It's one of the reasons Pantani is a legend (& yes, if Pantani is on the legendary list then so is Lance), i.e. people remember the crazy battles at the time between the best cyclists in the world. The Alpe D'Huez climb in 1997 was otherworldly (well, we now know what powered them but it was still impressive): Pantani, Ullrich & Virenque were on another planet that day & Ullrich himself was in one of the best forms you'll ever see a Tour winner in... yet Pantani still blew him off his wheel.
So truth be told Roglic could go to the Tour next year & lose against Pogacar, but as long as the fight is crazy & memorable, that's all it'll take to be "legendary" after the fact. And look at the riders Roglic fights against on every terrain all year: Pogacar, Bernal etc. in GT's, Ganna, Dumoulin, Dennis etc. in TT's & the likes of Alaphilippe in one day races. It's not like he's cruising around winning against nobodies.
This applies in other sports like F1 for example, i.e. where Ayrton Senna is considered "the best ever" despite only ever winning 3 titles because the competition & names he fought against made winning all the more impressive (& that's why Schumacher's best years were in the 1990's when he only won 2 titles whereas his 5 titles in the Ferrari aren't valued as much because of the sheer lack of adversity).
But then there's the battles of the particular era which mean more than numbers, i.e. the legendary fights people remember. It's one of the reasons Pantani is a legend (& yes, if Pantani is on the legendary list then so is Lance), i.e. people remember the crazy battles at the time between the best cyclists in the world. The Alpe D'Huez climb in 1997 was otherworldly (well, we now know what powered them but it was still impressive): Pantani, Ullrich & Virenque were on another planet that day & Ullrich himself was in one of the best forms you'll ever see a Tour winner in... yet Pantani still blew him off his wheel.
So truth be told Roglic could go to the Tour next year & lose against Pogacar, but as long as the fight is crazy & memorable, that's all it'll take to be "legendary" after the fact. And look at the riders Roglic fights against on every terrain all year: Pogacar, Bernal etc. in GT's, Ganna, Dumoulin, Dennis etc. in TT's & the likes of Alaphilippe in one day races. It's not like he's cruising around winning against nobodies.
This applies in other sports like F1 for example, i.e. where Ayrton Senna is considered "the best ever" despite only ever winning 3 titles because the competition & names he fought against made winning all the more impressive (& that's why Schumacher's best years were in the 1990's when he only won 2 titles whereas his 5 titles in the Ferrari aren't valued as much because of the sheer lack of adversity).