Something that I thought about a lot after hearing about the pacemaker (I haven't read the crossover and will be waiting on trade) was that as opposed to limiting Wally or altering the timeline with a questionable change to history, why not make Wally more powerful? What if Wally got so in tuned with the Speedforce he gained new powers but also had a problem of losing himself to the powers. Like he could use it too much and accidentally become one with the speedforce enacting it's will without even realizing he was doing it. Creating new problems from his powers like accidentally opening holes into other timelines, and giving him the option of going into different timelines or one that looks more like the world he lost. Maybe gaining the ability to make constructs and send them out scouring time for the entity that took the ten years from him. Continue on with the Rebirth plot with Doctor Manhattan and ultimately go nowhere until Geoff John's decides to do something with the plot, but build a B plot around that with Wally becoming progressively more manic over the situation and become more powerful to face Doctor Manhattan. What does it mean to be Flash? Well how about what does it mean to be human? Wally loses it and ultimately finds it again stronger for the experience. He isn't a redundancy, he's human who just happens to be a conduit for a lot of power. That would also have given major precedent to revive Hunter Zolomon and the tragedy angle to explore with Wally.
Hunter would've made a nice contrast to Wally now and he is just as fast as Wally is.
I don't know, I'm reluctant about the pacemaker and feel it wasn't a very thought through idea.