While the Speed Force has been overused and there are way too many speedster villains, the real issue is Barry himself. He's just been such a drag since Johns rewrote his origins. I would reveal this version as an imposter and get rid of him and whoever that Wally West imposter was in Heroes in Crisis kind of like they did the New 52 Superman - just a lot quicker, please. I would get back to having Wally as the main Flash again with Linda and (depowered, perhaps de-aged) kids in tow, pretty much where we left them at the end of Johns' run on the Wally Flash book.
I would then have proper, pre-Crisis Barry return and have them share the title. While Wally, a lifelong superhero, adjusts to the more grounded realities of having to look after a family, Barry (without the tragic origin, about the same age now as Wally and with a much more introverted and nerdy personality to contrast against the brasher, more sarcastic Wally) tries to adjust to a DC Universe that has moved on from him and that his nephew had fully made the title of the Flash his own. Keeping their established personalities intact would be central to the story going forward so Barry would be a man out of time but he would still be the same optimistic, morally-centered loveable nerd and Wally would still be the sometimes hotheaded but more mature Wally West that he matured into over Loebs' and Waid's runs.
I would keep both these character arcs as the underlying focus of the book and build on top of it stories that are pretty much like the Fantastic Four at its best: a mixture of family dynamics (Wally and Barry would be the main stars but other members of the Flash family will also regularly pop in and out of the book) and wild, crazy science-fiction adventures. There can and should be drama but the tone would also be in line with the more classic feel of writers like Waid or Busiek but perhaps with the added zing of Bendis or Fraction at their best.