User blog comment:LLight/WonderCon: Young Justice Season 2's Alien Invasion/@comment-69.120.211.237-20120429165422/@comment-1038387-20120504182655

For those who might be confused by the above: there's no confirmation that Barry Allen is dead in Young Justice, or that Wally West has taken over the mantle. It's just the way it was in the comics; Barry died (or, sort-of-died) in the Crisis on Infinite Earths in 1986, and Wally took over the mantle. He was the first sidekick who actually took over his mentor's name. He was never Nightwing, nor Tempest, nor Arsenal, nor Troia. He was Flash.

While we don't know if it's the case on Young Justice, there simply cannot be another way for Wally to mature than as Flash.