crazy idea: what if a big chunk of the first Flash movie takes place in the future, ala Back to the Future 2?
Barry is set to marry Patty Spivot. After the lab accident and a fight with Patty however, he accidentally runs extremely far into the middle of nowhere; not only in space, but in time.
He meets an adult Bart Allen, who informs him of the date, etc, and who shows him the ropes about his powers, the speed-force, etc. Here is where Barry gets his complex suit-in-the-ring technology (which was handed down to Bart (perhaps paradoxically) from Wally, and thus from Barry. Does the technology have no origin?).
A handful of the rogues are established and still around (because it's the future) and they all hang around together.
Barry learns that Bart was informed by Wally West that at one point in time, Barry died and Wally took over as the Flash, though nobody knows exactly when, how, or why (since they wear the same costume), and since the location of Wally West is unknown, so they can't ask him. Barry, unaware if he can change the future or not, is conflicted about whether or not to accept his destiny (and meet his death). He also learns that Bart's grandmother and his future wife is Iris West, not Patty, which complicates things.
At the end of the movie, Barry manages to get back to his own time; he saves the day from the villain who travelled back with him to kill him (in an attempt to change his future, eliminating Bart Allen from existence). At the end Barry chooses to accept his destiny, to be a hero, despite his eventual death. Although he repairs things with Patty, at the end he meets Iris West. Uh oh.
Perhaps the 2nd or 3rd movie can instead be dealing with the past (Barry's parents), ala Back to the Future 1.