McKenna Grace, Paul Rudd, Kumail Nanjiani and James Acaster would be my pitch for a great 'next generation' team given the set up we currently have. Rudd the smart mouthed leader, Grace the heart, Acaster the technobabble spouting brains and Nanjiani being the hands; each can fit one of those original GB archetypes yet bring their own aspects to the roles.
I'd love to see an adaptation of the comics storyline where the gang has to face off against a rival upstart organization that steals equipment schematics and bastardizes it to the point where they create a world ending threat but an entirely new other team runs in the possibility that you have too many characters yet again so I'm not sure. Perhaps it'd work if it was just a more singular 'Elon Musk' type who buys his way into the equipment and has no idea what he's doing with it.
One of the biggest problems I think the franchise is currently facing is that they're quite literally stuck in the bad catch-22 that is shelling nostalgia. They've created a great cast of new characters but I think they're deftly afraid of making a new movie if it doesn't have good stake of the original characters or story in it. I can understand why and I don't think it'll happen at this point but a new GB movie that is fine with shedding Stantz, Venkman, Zeddemore, Janine, Peck, etc outside of very minor cameos could have such a great width to spread its wings. I love GB, I love the original film, I have the logo tattooed on my arm but I'd be fine with a new GB movie that has Venkman on vacation, Zeddemore doing business in Europe and Stantz in a minor cameo role where he bigs up how bad this could be and gets to say funny nonsense for a scene.