I'll buy the game for $5 cheaper (used) at Gamestop a week or two after release if I have to. I'm not giving Konami any money whatsoever.
If you do that, then not only will you be shitting on Kojima and his team, but you'll also legitimize Konami's actions on this matter. They're doing this because AAA games don't make them as much money as their other ventures, so not supporting the people who ACTUALLY made the game only proves Konami right. Even if buying the game "new" won't change much in the long run, at least support Kojima and the team who put 120% into the franchise you love. You think Konami gives a damn if you buy MGSV used? They're a big company that makes the majority of their money elsewhere; they're basically releasing a game in a medium that they've mostly given up on. Boycotting them won't do a damn thing.
Kojima Productions is a different story. They're not going to make much money from anything else other than MGSV; this game is all they have, all they've been doing for the past 5 years besides PT. Their future is uncertain. We don't know what's going to happen to them after all is said and done. They have families to support, bills to pay. Imagine Konami's bosses striding into Kojima's office and telling him, "I told you so." Do you want that to happen? Konami isn't going to lose face if MGSV bombs; they've already moved on. They're done. Finished. MGSV is a Hideo Kojima game through and through. His is the reputation that's on the line, here. Konami has rendered themselves irrelevant in AAA gaming because of what they've done, so nothing you do will effect them. So forget them.
If you don't want to purchase Konami products after MGSV, then do so. But consider that MGSV's success will depend on total units sold through, meaning that every "new" game purchased is a mark of validation for all that Kojima and his team went through, and additional success and payment for all of their hard work. Prove, if not to Konami, then to the world, that games can be more than gambling bait, that they can be art, that they can be transcendental, that auteurs like Kojima didn't waste the last 25 years of their lives making games that gave you some of your fondest memories. Forget about not letting Konami win. Just make sure that Kojima and his team don't lose.