(thank you @gitwrecked for helping me get my thoughts in order <3)
When the EPs first revealed that Shiro wouldn’t be piloting the Black Lion anymore, my first reaction was “mmm, maybe not in your fic.” Despite that I can 'fix this’ in my own work, I was still a bit worried that this meant Shiro would be completely sidelined in future canon seasons. Would he be as strong and compelling of a character if he wasn’t in the Black Lion? Would we even get to see Shiro at all?
Season Seven utterly quelled those fears. I still intend to put Shiro in the Black Lion in as many pieces as I can, but - honestly?
If Shiro was still piloting the Black Lion, there’s no way they would’ve won that final fight.
Being in the Black Lion means that Shiro wouldn’t have been on the Atlas. Voltron needed as much assistance as they could get, both in the fight against Sendak’s armada and the second half against the Altean-Robeast-Scyther. Shiro was the one able to turn Atlas into the giant-mother-mecha who saved the day. The only reason Voltron survived both halves of the fight is because the Atlas, in both forms, was there to help.
If he hadn’t been on the Atlas, Shiro also wouldn’t have been free to destroy the crystal supporting Sendak’s ship. He would’ve been in his Lion just like the other Paladins, holding up one of the reflector panels to the zaiforge cannons. Shiro’s solo act to strike at the crystal on Sendak’s ship only worked because he could leave the Atlas to do it. He couldn’t have left the other Paladins.
It’s possible that Atlas could’ve had a different Captain if Shiro wasn’t there, but the battle would have gone much differently. Iverson or Sam could have captained the Atlas, but neither of them have Shiro’s battle experience against the Galra. Sam has experience with the Galra, but after Voltron freed him Sam headed right back to Earth with schematics and plans to prepare for the coming war. The Atlas he built is magnificent. That’s still a far cry - a different cry - from the countless battles Shiro actively led and witnessed out in space against the Galra, even on their home turf. Shiro knew the tactics. Shiro had the experience. Shiro was ready for this war.
If Shiro was still flying the Black Lion, Earth would have been doomed.
Growth happens. Growth implies a moving forward; part of moving forward means sometimes leaving things behind. I’m not just talking about people. I’m talking about entire parts of your life, sometimes, that get ‘left behind’ when another door opens. It doesn’t mean those parts of your life are any less valid. It doesn’t mean you can’t go back to them. It just means that if you do, they might be a little different than how you left them. That’s okay. The things you leave behind are allowed to grow just as you are.
Maybe one day Shiro will step back into the Black Lion to fly. That could be season eight. That could be after. That could be never. We just don’t know. He’s grown so much in the last season, though. Despite how much I miss him as Black Paladin, I can’t begrudge him this. In fact I’m pretty darn pleased. Shiro’s not reduced in any way for not being technical-Black-Paladin anymore. So many more doors have opened for him in just this last season alone. Are they different? Yes. Do they make him any less of a character or a person for what kind of doors they are? Absolutely not. The doors he’s already gone through and the doors he might go through next can’t change that.
Shiro’s a hero no matter what ship he pilots.