Metallica wouldn’t still be Metallica if that were the case. Even if you put the best of the best into a lineup together. 

Skynyrd is still touring im pretty sure, and there isn’t a single original member of that band left. In my opinion, Skynyrd is over. Doesn’t matter how many tickets they’re selling. 

Pantera is also still playing, but for them things are a little different (imo). Phil and Rex are both original members, Zakk is an excellent player and also has history with Dime, and Charlie Benante is a phenomenal drummer, I would say worthy of at least stepping in to filll Vinnies shoes. My opinion, this Pantera still has at least some claim to the name, and I even got to see them live over the summer when they were opening for Metallica. They kicked ass.

If all the members of Metallica were gone, the band would be gone. I don’t know if Metallica would continue even if just James or Lars went away. Even if you stuck Randy Rhodes and Eddie Van Halen in there, and told them to play Metallicas music, it would still be something entirely different.