You see, the majority of people of color, the LGBT community, young people and women have a brain, and they're smart enough to realize that what you're saying is, "Ignore the fact that we're working against your better interests and vote for us anyway because now we're saying it nicer!" That's just not gonna fly.
Now I don't think the GOP is going to go extinct, but their platform as it stands will only ever truly appeal to the most conservative. And I think that moderate Republicans don't agree with all of the GOP platform, but they still vote for Republican candidates because they still align *mostly* with them (and I'm sure couldn't ever bring themselves to vote for a Democrat). And all that is fine - by all means, vote your conscience - but it also puts both the moderate Republican voter and the GOP in an uncomfortable relationship.
Now, if a third, moderate political party were to spring up, then I could see the GOP becoming a fringe also-ran. (I don't see it happening to the DNC, because I don't think the DNC has been hijacked by fringe liberals nearly as much as the GOP has been hijacked by fringe conservatives.)