Though he should get a vasectomy to be sure...unless that would cause the end of the world.
And thus we have the eternal question from season one--why did Eddie kill himself when all he had to do was have a vasectomy?
Plus, because of the whole time remnant thing, Eddie's sacrifice meant absolutely nothing. In theory, it should have created a paradox. If he kills himself, Thawne isn't born, negating the reason to kill himself. Plus, Thawne couldn't kill Barry's mom, and Barry becomes Flash a little later in life.
Sometimes the writers don't handle time travel that well. I'm a believer that if you are writing a time travel story, you should open it up before publishing to nitpickers, including yourself. When someone catches something, change the story to deal with the problem. Once all problems are solved, you will have a tight story.
Regarding THIS episode, we have a situation where somehow, Nora was born, but Dawn was not. Why? The casual audience member wouldn't know who Dawn is, but she WAS mentioned by Thawne, who does. As he is immune from timeline changes, he knows how things originally play out.
I still think it would be absolutely amazing, and very gutsy, if the season ends with Nora causing herself to never be born, and Barry's twins to be born instead.
Well, there's a very good reason not to give her the cure because that would create another goddamn time paradox. As we see, also, that doesn't actually get rid of time travelling baddies either.
How many time travelling baddies as you say survived a timeline change that should have erased them? Obviously Thawne did, but he's also a speedster and the magical time remnant thing gives him a pass. Grace isn't a speedster, so I doubt she would survive it.
If Grace in the present was strong enough to take the cure, it might also get her out of her coma. The only issue that would be that Cicada I would be alive again, but that isn't the worst thing. He's depowered and going to jail.