The Kingsguard do not just swear off wives, but land and titles... in short, the abstinence of wealth and power. Bronn would never go for it. Never. He fights, works, protects, kills, investigates... and then he gets paid. He once told Tyrion something like, "I'm not your bloody brother. I sell my sword."
Brienne will be a Kingsguard only if someone with as poor judgement as Renly or with a feminist agenda (Dany) take the throne. I am not disparaging Brienne's abilities, but a female Kingsguard is not a protector, she becomes her own target. Prince Aemon the Dragonknight, Arthur Dayne, and BFS were not considered novelties, they were legends.
Jon Connington will never be one of Aegon's seven. That would be a demotion. The Knigsguard are the shields in front of the throne, Connington is already the power behind it.
Jorah (my favorite non-POV character) will only be a Kingsguard if Dany and BFS allow it. Dany might... according to the show.... yet my feeling that Dany is smart enough to know that Jorah was already too familiar with her. BFS will never allow Jorah in the club. Jorah dreams of redemption, personally and socially. He's a political pariah, it would be unwise to offend the northern lords just to give Jorah a white cloak.
Brynden Tully, aka The Blackfish, is a fairly enigmatic character. He's got the ability, but his pedigree is only good if the Stark-Tully alliance comes out on top. His age might be an issue, he's got to be mid-fifties now.
Victarion. He is a born killer, but he could not wait upon some king or queen in a castle. He is a ship captain. He's an admiral. Even if the Greyjoys somehow won and put Asha on the throne, he'd consider the Kingsguard beneath him.
Asha, like all the Ironborn, consider themselves as captains and individuals. She'd never wait outside a door while the person behind ate, drank, bedded, or did nothing at all. I'd never consider any Ironborn as Kingsguard.
Rolly Duckfield will get a white cloak if Aegon takes the Iron Throne.... if he wants it. Does a white cloak mean more to Rolly than land and titles? I don't really know enough about his motivations.
If Jon takes the throne, a wildling could be an option. They should be like the original Varangian Guard of the Byzantines. No one in the south could bribe them or seduce them. But a Kingsguard is the ultimate kneeler. Would a real son of Tormund even consider this an honor? I doubt it.
Tom o'Sevens is a wanderer... if he actually is who he appears to be. The Knigsguard serve in the Red Keep...... for life.
Harwin, son of Hullen (Master of Horse at Winterfell). I believe the Brotherhood are now a political liability for everyone. It does not matter if the Starks, Tullys, Lannisters, or Targaryens win... the Brotherhood must be eliminated. If Thoros were still in control, then maybe Melisandre could pardon them if Stannis wins.... If Beric were still in control then maybe they could get a pardon from Edric Storm or Gendry if they somehow win. Everyone in the Brotherhood needs to disappear... either be choice or force.
Timmett is an independent leader. I don't see him leaving the clans for KL... leaving leadership for service. When Julius Caesar fled from Sulla, he passed through a Gallic village that was just pigs and mud. One of his companions said he'd hate to live there, to which Caesar replied, "I'd rather be the first man in this pigsty than the second man in Rome."
Sandor Clegane.... what physical prowess is left to him? Strength? Yes. Keen eye? Yes. Savagery? Yes. Agility? Doubtful. Speed? No. Putting a cripple on the dais as a shield sends the wrong message to everyone. Oh yeah, he deserted and then turned brigand last time he wore a white cloak.
Nymeria Sand. She's a master of the deserts, swift strikes, and revenge. But how does that fit in with the traditional male heavy armored knights of the Kingsguard? She does not fit, even if the Martells win. Obara might, but not Nym.
Grey Worm is the commander of the Unsullied. Another Unsullied could wear a white cloak, but not their commander. The remaining Unsullied after Dany's conquest may become the official guard of the Red Keep (the Lannatheons called them Gold Cloaks) or the city watch of King's Landing (the Red Cloaks). It makes more sense to me if Worm's cloak is ultimately some color other than white.
No one mentioned Daario, so I'll go ahead and shoot this nomination down now. He's a loose cannon. He's too familiar with Dany already. Dany should be wise enough to know that Daario needs to be given lavish gifts and sent on his way.... or fed to a dragon.
BFS is a no brainer. Even if he's lost a step (and his fights with the gladiators show he has not), his knowledge of Aerys II, his knowledge of the Kingsguard, his knowledge of the Red Keep, his knowledge of protocol, his unquestioned honor, and his legendary status make him the single best choice as LC of the KG.
Podrick Payne. A sentimental favorites of readers and viewers. I'd love to see him rise high, but who is going to offer him the job? Tyrion is the only one. Pod's coming along as a fighter, but he's not great... yet. He brings no political allies with him. He brings no commercial connections. We know of his unshakeable loyalty... and the only way he'll get a white cloak is for Dany to see it as well. And don't think that GRRM does not know this...
Good topic, Narky.
I don't believe Loras is dead. I don't believe Loras is injured. I think the Martells are keeping him safe from harm while seeing how Tommen's reign during Aegon's invasion turns out. If the Lanatheons are winning, Loras will show up to lead the charge. If the Targaryens are winning, then Loras can join Aegon while Margaery escapes KL. Loras could be in Aegon's KG.
Lyn Corbray. He's a real snake. According to Littlefinger, he only likes two things.... young boys and killing. The KG can kill... and swear off fathering children... I can picture Littlefinger sending him as an assassin or more likely a sleeper agent. It was fortunate that the rebels (Robert's Rebellion) had an inside man in Aerys' KG... Jaime. Littlefinger knows the benefits of agents. Even now, the Kettleblacks may still be in his employ.
If Littlefinger finds out who Shadrich, the Mad Mouse, is. He may turn him and send him back to KL as a double agent. Could Shadrich end up on the KG? He will if Littlefinger wants him there.
The Freys are starting to kill each other in their scramble to succeed Lord Walder. Look for one of the better (and smarter) ones like Red Walder to cut a deal with Black Walder and join the KG as continued recompense for the Frey's treachery.
If the Lanatheons continue to survive they might recruit the Strongboar.
In the end, I would not expect many KG to come from powerful houses or most noble houses. The fighting has left many families without an heir, let alone a spare.