If only they treated time travel properly this might not turn out how he expects.

Originally Nora Allen was killed by an intruder and not Reverse Flash so if they do this properly all that changes is that the Reverse Flash didn't succeed in killing Nora and fled back to the future because he didn't mess up the time stream.

That mess was the fact his run into the past drew the Flash along with him so by driving off the Reverse Flash should erase everything the Reverse Flash did restoring Eddie and more importantly Barry's dad and everyone else the Reverse Flash killed between killing Nora and before Eddie shot himself.

That should also seal up the breach, but would require Barry who should retain all memories of this time to figure out a way to breach into Earth 2 and deal with Zoom rescuing Jay along with meeting Super Girl as I believe that was where Jay claimed to come from wasn't it?

We could be introduced to Harrison's wife and their version of his daughter, more importantly I suspect Barry's interference may still lead to them getting powers although they might not remember how and why.

You know that repeated travel into the past might have been the source of Barry's powers as well as the Particle Accelerator accident rather than it sparking his powers now that would be quite a nasty revelation wouldn't it?

So assume Barry tries to maintain the timeline probably remembering the Pied Piper so he remained good.

If this was the case would Black Siren be still stuck in containment or would Barry use this opportunity to save Laurel insuring she didn't die?

There's a lot of way this could be done right but given previous developments I'm just hoping they don't screw this up!