Legacy won't draw in anyone new. It'll bring back some old fans, just like Picard Season 3 did, but that's the extent of it. It's not about a new beginning, it's about extending Picard without having Patrick Stewart. PIC Season 3 laid the groundwork for how they could do that.
As far as the "nostalgia" angle, that's only half-true. Half very, very false. These old fans will come back to watch Legacy, just like they did Picard Season 3, but then a lot of them will react like, "But it's not the way I remember it!" It'll be shot differently, it'll be lit differently, it'll be paced differently, and the use of language will be different from TNG/DS9/VOY.
So true in the sense that the old storylines and characters will be revisited, false in the sense that it'll be written and produced in a different style. That was the draw for me with Picard in general. Seeing Berman characters back in a non-Berman style. That's the reason I like it. Yes, it's the same characters. But it's a different spin on the characters.
If you want completely new characters in a completely different setting with everything in the galaxy all shaken up, then Star Trek: Discovery is that. With the exception of "Unification III" and the two-parter where they wrote out Georgiou, Discovery has been largely devoid of "fanwank" and "nostalgia" since the beginning of its third season. "But STD sucks!" Then you like the idea of something different, but you don't like the reality of it.
"Continuing TNG sucks! Let's do another TOS reboot!" So you all want to replace one type of revisiting with another type of revisiting. Pot meet kettle. "But it's a different type of execution!" Once again, pot meet kettle.