1. I would really want a Sparda game where it takes place before DMC3 because its perfect time for Sparda to get his spotlight.
2. New weapons introduced such as Double Spear with Fire element, Both Sided Scythe, Huge Axe just like Agony Axe from Spawn Armageddon, Sword Whip, aaannnd... so far that's all I could think of.
3. A story about how Sparda get his Force Edge, Yamato and Luce & Ombra gun.
4. A story about how he met his first love with Eva.
5. A Bloodborne-ish theme setting where it takes place in Victorian Era.
6. A Bloodborne-ish music remix with rock and orchestrated gothic battle theme with enemies and bosses.
7. Sparda and a group of Vie De Marli takes on hordes of deadly demons in Dumary Island and facing the full power of Argosax The Chaos, maybe as the penultimate boss before facing the true final boss, Mundus himself.
8. More costumes, more enemies, more bosses, more stages, more weapons, more cutscenes, etc.
9. Sparda's 3 new sidekicks, Martier, Baul and Modeus.
10. Going through stages such as Temen-Ni-Gru, Mallet Island, City of Fortuna, Dumary Island, Demon World, etc.
This is how Sparda should look like in the next-gen consoles.
http://www.deviantart.com/art/The-Dark-Knight-Sparda-511557690
And his bad-ass alternate costume
http://croaky.deviantart.com/art/DMC-Sparda-Secret-mission-122191198
Personally, I wouldn't have name it as Devil May Cry 5 but I would name it as Devil May Cry 0: The Tale Of Sparda. Thus, I made a cover box art for Sparda game few months ago.