This might be too many, but what I want to see remade, remastered, or given complete editions (although "complete editions" may not be relevant to the post topic; and some titles may not be considered niche but whatever) are Asura's Wrath, Bloodborne, Bujingai, Bully, Dante's Inferno, Dark Sector, Dead Rising 2 (and Off the Record), The Dishwasher: Dead Samurai, the F.E.A.R. series, From Dust, God Hand, Grand Theft Auto IV, the first two Gungrave games, Just Cause, killer7, L.A. Noire, the Legend of Spyro trilogy, Like a Dragon Kenzan!, Mary Skelter 2, NieR: Automata, NieR: Replicant, Ninja Gaiden Sigma, Ninja Gaiden: Dragon Sword, Ninja Gaiden Sigma 2, Ninja Gaiden 3, No More Heroes 2, Prototype, Red Steel 1 and 2, Rising Zan: The Samurai Gunman, Solatorobo: Red the Hunter, Spec Ops: The Line, the original Splinter Cell (plus Pandora Tomorrow, Chaos Theory, Double Agent, and Conviction), Stranglehold, Tail Concerto, Viewtiful Joe 1 and 2, Watch Dogs 1 and 2, and the original World Ends with You.
Primarily, the goals would be to either restore cut content or integrate separate DLC into the main package, offer enhanced graphics, take advantage of the 16:9 aspect ratio if originally released during the time of 4:3 screens or on handhelds, or fix bugs or address technical limitations that affected their original console or PC releases, alongside numerous quality-of-life improvements like anti-cheat and DRM removal and extensive performance optimizations. Also, we're still waiting for a PC release for Bloodborne.
Because I'm concerned that both their current PC versions still remain buggy messes. I'd wait until the devs provide updates on those to address these issues.