Like every other guy I would love for more females to join because…fan service.
So, I not the biggest fan of Bartolomeo but I can see him joining the ship for a while if not becoming a full time member of the crew.
The thing that people write on here most of the time is about dreams and positions. I would agree that you have to have a dream to part of the Strawhats but I don't really buy into the position within the crew. I would sum it up to "desire". Luffy had a desire for Zoro because he needed strong members for his crew. Then he needed a Navigator, Cook, Doctor, Shipwright, and Musician. I know you don't really "need" a Musician but according to Luffy you did. As for Usopp and Robin, Usopp had the desire to go out to sea and Luffy told them to board the ship, while Robin needed to board the ship because she didn't have anywhere else to go. They both later had the "desire" to join the crew and ended up asking Luffy to join. I would also add Brook into the second group as well since he also asked to join.
So that's why I think, as of right now, Bartolomeo has a strong chance of joining the crew. 1. He is starting to be liked by Luffy, at the least Luffy doesn't see him as a bad guy. 2. He has a desire to join and might ask to join the crew. If he asks to join or board the ship I don't see Luffy saying no.
My hope is that Bartolomeo becomes a Mr 2 type character. Since none of the Strawhats are now in the coliseum story, I can see Bartolomeo staying behind so that Sabo can join up with Luffy after the getting the Mera Mera fruit. I just can't see anyone just being "awarded" the fruit with any chaos at this point because of all the craziness that is going on within the island.