It's all down to the interests of the talents if they are willing to collab or not. If they don't want to, then please respect their decision. Otherwise don't force them to collab and let it happen naturally.
I'm going to give you a list of all the Hololive talents and tell you the chances of them collabing. Grouping them by Generations:
Gen 0 - Sora, Roboco, AZKi, and Suisei all have already either collabed or directly interacted with a Holostar on stream, so they are safe. Miko is the only one who will not collab with a Holostar or any male on the case that she wants to "preserve" the idol image.
Gen 1 - Fubuki and Matsuri have already collabed with Holostars. Aki Rose has not directly collabed with them as far as I know, but she does support them and will retweet some of their events on Twitter, so a collab can be possible. The chances of Mel collabing with them is very slim due to the incident that happened to her a few years ago. There is no chance that Haachama will be collabing with Holostars at all since she has Gachikois up the ass.
Gen 2 - The three introverts are out of the question. Choco has both directly collabed and interacted with the Holostars, and she is cool with it. Subaru to my knowledge has never collabed or interacted with the Holostars, but given her open tomboyish nature, she may have a good chance of collabing with them if the circumstances allow it.
Gamers - While they share common interests with the Holostars, chances are they are not willing to collab at all probably due to social anxiety. Mio probably has the highest chance of collabing with them...which is extremely small, so don't expect anything.
Gen 3 - ABSOLUTELY OFF LIMITS. Pekora like Miko wants to preserve the idol image as she says, and her popularity would cause way too much drama if she does interact with a male talent. Marine, Flare, and Noel all come from an all-girls school, and interacting with men would be too troublesome for Flare and Noel. Marine would probably be fine with it...but she's got Gachikois up the ass.
Gen 4 - Kanata is a pretty busy and reserved person, so she probably has no interest in collabing with the Holostars. Watame tried to interact with them early on, but she got flamed for it by her fans. I am glad that she is at least aware of them and acknowledges their success, but the chance of a collab is very slim. Towa has not directly collabed with any Holostar, but she fully supports them and is open to collabing with them. Luna...is in a weird spot. I don't think she minds collabing...but Luna is..kinda difficult to collab with...
Gen 5 - I'm personally surprised that Botan has not collabed with a Holostar yet given her skill in games, but I assume that she's not the kind to generate competition since she's veering away from it. Also, I think it was during the Battlefield casual tourney where she teamed up with a male vtuber, and her fans didn't like it, so sadly a collab with a Holostar has a very low chance. Lamy has gachikois up the ass, so not happening. Nene asked her fans if it was ok for her to converse with males. Her fans said no though. However, I do remember her tweeting about Oga and the dice game he made a while back, so the cards are not out of the table yet. Polka is the only member of Gen 5 who I know openly supports the Holostars. Polka has the best chance of collabing with a Holostar, but she'll have to work on her social anxiety first.
Gen 6 - Not happening with La+. She's a Hololive fan herself, and she says she gets upset if anyone collabs with Towa male or female. Lui...I don't know her opinion yet, but I wouldn't say the chances of collabing with a Holostar are zero. Koyori takes after Fubuki so much that I hope she can collab with them, but we can't force her to, so it'll be up to her. Not happening with Chloe. Gachikois up the ass. And Iroha I don't know too much of, but we'll see.
