As others have said, it depends on what version of time travel they go with. The show seems to be going for a mix of two time travel theories:
A.) When you travel back in time you actually just create a new timeline
B.) Going back in time can change the time you came from.
We've already seen examples of B in the episode where Barry lost his powers and it changed Wells' article that he always references. We haven't really seen A yet, but the actor who plays Cisco has said we will revisit the timeline where he's dead. So both ideas seem to be at play.
Given that, I figured there are two possibilities.
1.) Barry Prime was erased from existence when Eobard killed Nora
2.) Eobard killed Barry Prime in his attempt to get at little Barry.
Option 1 only works if they go with the Option B time travel rules. Option 2 would be the best way to explain Barry's absence if they go with the new timeline idea. I'm sure there are other options, but I haven't thought of one yet.
Either way, it seems pretty clear that Barry Prime is either dead or erased, because RF was cut off from the speed force, and it seems he only has access to the SF if there is a Flash. So Barry Prime can't have been trapped in the past like Wells.
Do you have a link to where he said we will revisit that timeline? It fits with what I thought happened and why there wasn't 2 Barrys.
I think there are different types of time travel on the show. I don't think that Barry just went back in time I think he created another timeline. People keep saying they merged. But how it played out on screen is Both Barry's saw each other, and from their perspectives the other disappeared. And we saw both of them continue and the other disappear. The point that they saw each other would be the divergence of the timelines. So that would mean the timeline, with the tsunami, continued on without the Flash.(also could be a start of a little Multi-verse)
When the Flash is able to control what he does he'll be able go back in time without creating a new timeline and if you change something there it will change the future. I think Wells always checking to see if the future has changed shows if you change something in that timeline it will change the future in that timeline.
I think that other timeline that was created will play a bigger role this season. Wells in that timeline would be stuck. In the promo there were 2 Flashes fighting each other. Maybe he helped create a new flash(maybe eddie).