Mr Richelieu, I'm sure you have inherited at least some of the skills of THE Richelieu himself
the war will indeed be pointless for both Russia and Turkey, but a lot more pointless for Russia which will loose more in diplomatic terms than it can gain. However it will not necessarily be pointless for the enemies of Russia.
As for capturing Istanbul....
...does Russia have the ships to transport such a number?
Classic NATO is dead; current NATO is USA, Eurotrash, and a few very unwilling allies like Germany.
Turkey should look to its defenses, and rapidly fill in the gaps. If the US comes knocking in future, if the Turkish govt is wise, it'll not ask for what the US is giving, but will demand what Turkey wants. That's how Zia negotiated with the US.