Sure there's a possibility that Gallagher could break into the mainstream, but typically child actors don't do this. I think he's going to be one of the child actors that is only ever known for his past on a long running, but poor quality tv series.
Of course Gallagher would be cheap, and would willingly play Flash. I'm sure he'd do most roles, as he probably would like to be more famous than he is. But i fail to see the point you're making here... Carrot Top would also be cheap and would be willing to do the role... See where I'm going with this?
Actors break out when they're over 30 all the time. But typically if a former child star is going to break out into the mainstream, it'll be before they are 30. He's been in the spotlight since he was a child. He's had plenty opportunities to blow people away since the 90s. I think if Gallagher's career was going to take off, that it would have already happened.
I could be full of **** though. But i think it'd be a good move to cast someone who has a lot of fans already and who's face they already are familiar with. When people see Aaron Paul, they associate him with a fantastic television program (maybe the best of all time), and when they see David Gallagher's face, they either associate him with nothing, or a very poor television series. I don't think anyone should be thinking about 7th Heaven when they think about Flash. People shouldn't be thinking about Breaking Bad either when they think about Flash, but associating a lesser known character like Flash with a high quality television series like Breaking Bad wouldn't be bad for business.
Gallagher being cast as Flash either negatively impacts box office (by association with a poor tv series) or he doesn't have any impact on the box office returns at all...
It'd be smarter to get an actor who actually positively would impact box office returns. Casting an actor who can draw in audiences just by being in a movie is what this character needs. That actor is Aaron Paul. The dude is massively critically acclaimed, but he still hasn't completely broken out on film into the A-list. He's like Jennifer Lawrence pre X-Men First Class. They should get Aaron Paul while he's still cheap and willing to do something like this.
Gallagher is completely wrong for this role.
Gallagher or Mazzello for Snapper Carr. I'd be happy to see either of them in a small role. But I'm not clamoring to see either of them join the DCU.
Also in regards to Mazzello, I haven't seen GI Joe Retaliation, I don't know what the Pacific is, and I've seen parts of The Social Network and don't remember Mazzello's role. That's decent exposure, but he's still not really on anyone's radar.
With Flash, you have to keep in mind that this is a character that has the potential to lead his own movie. Do Mazzello or Gallagher have what it takes to lead a massive tentpole movie like The Flash? Airwings, you seem to believe in these guys, but I'm not so convinced. I'll keep my eye on these two, but as of right now I'm definitely leaning towards a no for both of them.
Aaron Paul's schedule seems to be clear for him to play Flash right now... and when Aaron Paul is an option for Flash, it's really hard for me to even consider other actors for the role. He would bring a lot to the table, and would be a very smart and respectable business decision on WB's part. That's what all this is really about... business... and an Aaron Paul led Flash movie simply has a better chance at being successful than Mazzello or Gallagher as The Flash.
Mazzello and Gallagher would make more sense as suggestions for the CW Flash tv show.
Sorry, i look like I'm bashing your opinion. You clearly believe in these guys, there must just be something I don't see. Like I said, I'll definitely keep my eye on these guys. But right now, it may seem narrow minded, but I think the Flash actor needs slightly more star power to give the character a box office boost.
Just imagining the chemistry these two would have on screen...
