Even though this concept was supposed to be a “One and done” kind of thing, I’d really like to see a next gen sequel to BattleFantasia.
I mean the two main characters (Urs and Marco) start off as kids in the first game, but what if in the sequel it shows them all grown up, while also becoming full bound badasses after the final events with DeathBringer?
Plus the idea of mixing RPG elements with a fighting game is something I think could really be expanded on.
I’d say
Tony Hawks American Wasteland… I wanted a second one. It was blatantly Jet Set Radio inspired 
I love it.
Unfortunately Robomoto’s shotty development of several Tony Hawk games, may have doomed the franchise.
I would generally like to see a JSRF & THPS hybrid type thing…
If we’re talking games that never received a single a sequel, I’d say:
Lost Odyssey
Crimson Skies
Skies of Arcadia
Weaponlord
Nights
Kameo
Mace: The Dark Age
Kakuto Chojin
Tao Feng
Cannon Spike
Final Fantasy Tactics (console)
Ehrgeiz
Star Wars: Masters of Teras Kasi
Psi Ops
Blood Wake
Eternal Darkness
Super Mario RPG
Conker
Captain Skyhawk
Blue Lightning
Kasumi Ninja
Solar Striker
Ico
Aggressive Inline
Now if we’re talking dead series that need to be brought back (with a sequel), I’d say:
MechAssault
Blood Omen / Legacy of Kain
Sonic and Sega Allstars Racing Transformed
Hunter: The Reckoning
Bloody Roar
Battle Arena Toshinden
Power Stone
Alundra
The Strike series (Desert, Soviet, Jungle, etc)
SSX
Shining Force
Shinobi
Darkstalkers
Fighting Vipers
Panzer Dragoon
Silent Hill
Primal Rage
Jak and Daxter
Last Bronx
Virtua Fighter
Soul Calibur
Dragon Force
Loaded
Streets of Rage
Maximo
Gargoyles Quest
Rallisport Challenge
Eternal Champions
Rogue Squadron
The Darkness 3
Conker’s Bad Fur Day 2
Dead Space 4
Darksiders 3
Ori and the Blind Forest 2
Virtua Fighter 6
Mega Man X9
Mega Man Maverick Hunter X2
House of the Dead 5
DOOM 2
F-Zero
Medievil
Eternal Champions
Virtua Fighter
House of the Dead
Wow, this list includes all of my own favorites. I 100℅ approve your list 
Most games listed by others in this thread already have sequels (however obscure) so it’s basically been derailed.
Here’s my list:
Mario Paint
Lost Odyssey
Limbo
Castle Crashers
Crimson Dragon
Shantae. I just played through Shantae and the Pirate’s Curse and Shantae: 1/2 Genie Hero, and they are so fun. We need more sequels to Shantae.
-Jagged Alliance: Just someone make third installment (or remake JA1) that wont suck already.
-Splinter Cell: Blacklist was step in right direction and three separate playstyles turned out to be surprisingly well done imo. Altough Fisher is too OP when you unlock more gadgets and who the hell decided to replace Michael Ironside as Sam`s voice actor.
Get back Ironside as Fisher, hire Amon Tobin to compose music again, balance it better.
But knowing Ubi these days they will do some lame open world crap with copypasted missions and overpowered gadgets purchasable with real money.
