Barry saves Nora, and Thawne kills young Barry, making Barry a paradox, and then, well, something weird is gonna happen.

Probably we'd just see Flash return to a future where Eobard still took over well's knowing that he was the key to creating the flash. Hoping that instead of Barry another speedster would arise.

In that world we see barry encounter a city conquered by Grodd, who in this time line has asserted his power's faster due to the city being in more chaos as a result of the metahumans and has them under his control.

But Barry is fading, unable to maintain his existence. He's a man who shouldn't exist.

He encounters Eobard who has been defeated/actually paralyzed for irony's sake by Grodd. Eobard realizes that if barry exists now then there is a chance for it all to be undone. He tells barry that he has to go and save himself, for this time is doomed and if he stays barry will fade away and they will have no hope.

Barry refuses and tries to fight Grodd, knowing that refusing means his mothers death, but is unable to be an adequate matchup and begins to fade even faster as he uses up even more of his connection to the speedforce

Barry might find out that following his death, his family hit a dark patch and although he saved his mother, she was never the same and retreated into herself. Following an encounter with her, she somehow realizes that Barry is her son and they have a final goodbye. Before barry returns to the night his mother was supposed to die. Merge's with his original self. Much like he did in episode 15 and allows his mother to die.

Then you have the season 2 intro be

"My name is Barry Allen, The fastest man alive, I achieved the impossible and saved my mother, But the cost was too high, I have been to the future, I thought my mothers killer was my greatest foe and her death my biggest loss, But I know the truth, he pales in comparison to what's coming. But I will be ready when he arrives. I am The Flash"