Is this at all possible? I've been thinking about it recently and I think it'd be a great little Bad Karma sorta thing to do, but I've got no idea how to do it, because once you sell Arcade off the mission Auld Land Syne of course becomes impossible, and he leaves you forever if you side with the Legion.

I was thinking of perhaps getting to the last stage of Auld Lang Syne, selling him, and then coming back to complete it, but that might just butcher my game and make it an unholy glitchfest.

Does anyone have any knowledge on this issue, or am I up a particular creek without a paddle?

Couldn't you sell Gannon after completing Auld Lang Syne? I have only done this quest once, and I know it comes later in the game during the third act, but is that too late to sell him and switch sides?

Doesn't Gannon leave you as soon as you complete Auld Lang Syne?

Maybe sell him after you get access to the Remnants Bunker, but before talking to them...

no he forces you to talk to him after you leave the bunker either to thank you (if siding with NCR) or getting really pissed if you have the Remnants exact their revenge

methinks theyre mutually exclusive