As much as I love the idea that the dead poets would all still be friends after Welton I have to put into perspective how Neil's death effected them.
Charlie got expelled, he lost his best friend. In the end he hates Cameron. Maybe he'd keep in contact with Meeks or Knox and maybe check in on Todd but he's definitely be too crushed those first few months. He wouldn't be able to talk to ANYONE. Plus the pressure from his parents because he got expelled? He'd crumble. He wouldn't kill himself but he'd definitely be too upset to keep in touch. He took it the hardest even if it wasn't shown.
Todd only truly knew Neil, sure he was friends with the others but NEIL was the one he was close with in the end. Him and Charlie might bond with their grief but I doubt Todd would be able to talk to most of them for a very long time after Neil's death. Yes he still goes to Welton but he shuts back into himself again once he truly realizes Neil and Mr. Keating aren't coming back. They were everything to him.
Cameron was pretty much outlasted from the Dead Poets. He's kinda seen as why Charlie got expelled in the end and they don't like his viewpoint on what happened. He might still talk to Meeks and Pitts but NONE of the others. They have a hard time understanding that Cameron is just a kid as well because their friend who was just a kid is dead. He might make other friends at Welton but he's pretty outcasted from the rest of the kids as well.
Meeks and Pitts would definitely still try to check in on anyone. They both were friends of Neil's but they weren't as close to him. Yes they were still CRUSHED but their minds are less fogged with grief. They fade away from the others and eachother but they stay friends.
Knox strayed away from everyone. He wasn't as close to Neil as some of the others but Neil was his brother. Him and Neil just clicked like that. He loses Chris because he shuts in on himself after the death. Losing Chris was his last straw and he gets caught trying to kill himself. He strays even more away from the others after he gets removed from Welton and put somewhere else. Charlie and Neil were his buddy's, without them he doesn't know what to do.
Most of this is headcannons in the end but people need to remember these guys are just KIDS. They still have so much more life ahead of them. Neil was the glue that kept them together and the Dead Poets disband for good.
