Goal of NATO is “to safeguard the freedom, common heritage and civilisation of their peoples, founded on the principles of democracy, individual liberty and the rule of law. … to promote stability and well-being in the North Atlantic area.” [1]

Russia joining NATO in good faith would change it for sure but would not make it obsolete.

[1] https://en.m.wikisource.org/wiki/North_Atlantic_Treaty

That’s your argument? You googled and pasted in their mission statement?

Who would that alliance be (ostensibly) protecting themselves from? China? Taking that kind of stance (EDIT: against China) would not be in Russia’s interest.