Whatever it is, hopefully Vergil gets something more than just the usual Yamato + Yamato & Force Edge + Beowulf setup.
He needs a proper story where he explores and collects his own set of Devil Arms.
It could even be some story where Dante gets knocked out and drops his Balrog set, allowing Vergil to pick them up (a reference to how Dante picks up Beowulf dropped by Vergil).
Its stated in the DMC5 prequel novel Balrog only became Dante's Devil Arm so he can collect battle data while Dante is using him (which is why he can talk during gameplay) and become stronger so they can have their rematch. So that novel (which is written by the same writer as the games and Itsuno approved) sets up Balrog's return and rematch. I wouldn't be surprised if say in a Vergil campaign Balrog makes due with his promise and returns for his rematch only to fight Vergil instead, lose, and become Vergil's Devil Arm.
In his boss fight they shown Vergil capable of using Helm Breaker and Stinger through just Yamato alone. They'll probably just squeeze whatever moves of Force Edge into Yamato and whatever they can't fit into another weapon. DMC4SE didn't capitilize on the newer inputs DMC5 now capitalize on so there is plenty of room for his Yamato moveset to expand.
Unfortunaly, we can only hope for Capcom to get that DMC deserve far better. For me, a game like DMC deserve to have the success of DOOM with the 2016 game and DOOM Eternal. But to get to that point, the serie need to get back on foot and have a good scenario and put on a good show. I see DMC 5 ending as the starting point for this. The Sons of Sparda arc is over, there isn't any stories going on, and Nero ended his development when he got his DT. Plus Capcom seems to have plans for the future of DMC, so there is an opportunity to make DMC great again that musn't be missed.
As shown with SFV and Monster Hunter World it seems Capcom are adapting their business model to be more current. DMC3SE couldn't really exist any other way and only exist to fix how they botched the difficulty in Western territories and DMC4SE was a rushed product (Itsuno admits this). The higher ups keep saying stuff like how the game exceeded expectations, rejuvenated the brand, they're treating it as a core franchise (I guess that means alongside RE, SF, and MH), how they've hired or hiring new recruits or fresh talent who are excited to work on DMC games, and more.
https://nichegamer.com/2019/10/16/capcom-teases-future-devil-may-cry-titles/
http://www.capcom.co.jp/ir/english/data/pdf/annual/2019/annual_2019_01.pdf
Couple with all the accolades and the fact the game won a GOTY award the higher ups must either must be insanely stupid (considering Capcom's history plausible), have some grudge against this franchise (maybe Kamiya ****ed in someone's cereal before he left), or be insanely stubborn to not to.
Coupled with some anime (potentially) coming out soon which would make for some great cross promotion (as well as the fact the series 20th year anniversary is next year) they would be UTTER FOOLS to not (eventually) capitalize on the insane amount of clout this franchise is getting lately.
Then you have how they are adding some new feature(s) to a port of a 15 year old game that they've ported elsewhere 3x already. I mean fans weren't even asking for them to update DMC3 (they were instead asking them to update DMC5 lol) and would be happy to just get DMC3 on the Switch but they're doing it anyway.
Then again I can't see the future nor do I work for Capcom (as well if they were working on something there would be credible leaks by now like there was for RE3 Remake) so all I'm saying just makes sense to me but Capcom.....honestly sometimes lack common sense or running a multi billion dollar business is a lot more nuanced and complicated than we think it is.