It sure seems, from the context of an EW Spoiler Room column, that the forthcoming The Flash/Arrow two-night, two-part crossover will give Jay Garrick his powers back by introducing Velocity 9 to the TV series.
Velocity 9 is, in the comics, a serum that can bestow (or in Jay's case restore) super-speed powers. It's just one of a number of artificial ways to gain such powers, one of which is the Speed Formula -- a literal mathematical equation that Johnny Quick and his daughter Jesse Quick both used to gain speed.
Of course, on TV, Jesse Quick's father is Harrison Wells who, as far as we can tell, helps to develop Velocity 9 here:
“Jay is summoned to S.T.A.R. Labs in an urgent matter from Wells,” said Teddy Sears, who plays Jay Garrick on the show. “Jay shows up only to find out that Wells wants Jay to be his guinea pig. He is toying with a substance that has its history in the lore of The Flash, so it’s something from the comics. He wants to try it on Jay to see if it works because he wants to use this on Barry in their fight to bring down Zoom. Jay doesn’t react very well to that. He doesn’t want to be a part of Wells’ schemes. There will be some life threatening moments in there and we have to use a combination of science and ingenuity and Wells’ mysterious substance to get to a safe conclusion.”
Obviously, they don't say the word there...but that, combined with earlier hints that Jay could get his powers back during the crossover, seem to indicate it's a good possibility.
The serum had some serious long-term health effects, with the effects of the Speed Force taking their toll on people not prepared to connect to it. The most recognizable regular user was Inertia, the arch-enemy of Impulse and an evil speedster who at one point lost his powers.
Interestingly, Velocity 9 in the comics was actually developed not by Wells (who doesn't exist in the source material) but by Vandal Savage, who will be the villain in the crossover episodes and the Season One big bad for DC's Legends of Tomorrow. Savage ended up running a small drug empire after sales of Velocity 9 to successful young men put him at odds with more traditional drug dealers.
Of course, if it works, the next question is: Could Wells become Johnny Quick? Or even just don the Reverse Flash outfit again? Certainly, his daughter could use all the help she can get right now.