I think that if a PS5 sku of TLOU2 ever exist, it will only be a digital sku and a PS5 patch for existing PS4 version owners. I think it would only be released in retail if bundled in a Director's Cut with TLOUP1 or TLOU Online.I wouldn't mind tlou2 ps5 native port but hope it's physical release.
Somewhat similar to what they did with Spider-Man Morales + Remastered or Uncharted thieves collection. Or the director's cuts of Death Stranding or Ghost of Tsushima, but this time instead of adding new DLC as extra content, they'd add TLOUP1 or TLOU Online.