On Topic of Both Dante AND Vergil Getting in, I Actually see it being very Possible if Dante gets in that Vergil also gets in. Vergil, when it comes to Reception is like Shadow in a way (My Most wanted Character), only he isn't a Base breaking character like Shadow is, and is so above the other Characters in Popularity Besides Dante (by Comparison, While Shadow is 2nd most Popular, I don't think he's as above Tails, Knuckles, and Eggman like Vergil is above Trish, Lady, and (Arguable) Nero)
-All of the Best DMC Games have been determined by the Amount of Presence of Vergil in them. DMC3 is arguable (with DMC5 also) Considered the Best DMC Game and that game is Vergil's Story as much as Dante's. by Comparison DMC2 has no Vergil at all and is considered the Worst game, and DMC:DmC has Fake Vergil in reboot universe, not actual Vergil
-Vergil Can take enough Material from Dante himself while also Separating Himself not only unique from Dante, but from the Rest of the Cast. Vergil (well in DMC3 anyways) Uses Dante's Model, but with his Hair Spiked up and Different Clothing. Also Alot of Vergil's Moves using Force Edge or Beowulf come from Dante, or are inspired by him. His Yamato Skills and Summoned Swords are really what Separate him from Dante, and can seperate him from the rest of the Cast. At the moment no one Uses a Katana, and unless Ryu Hayabusa gets in I Don't see any other Katana user getting in, and Summoned Swords as Projectiles, while could be hard to balance, are certaintly unique ways of using Projectiles
The Idea I Have is that when Developing Dante, they could use Alot of what they use to develop Dante and transfer it over to Vergil. I Already expect that Dante would probably have the Biggest Moveset in the game. I guess though an issue is that Vergil might have Balancing issues, but I can see it working. I guess also they would have to make Vergil Concept Art, Hire Dan Southworth to voice act, make sure that he doesn't leak anything beause he has an habit of doing that, make a Classic Route for Vergil. I do think though despite all that it's something I can very well see Happen. I Would definitely Want to see this Happen, as Vergil is the Type of character I want, like Shadow. If he got in, I would be down for waiting like 5 decades more for Shadow to be Playable.