The prequel comic to the new Trek movie isn't the only thing that suggests Data's alive. One of the "official" online sources has info that ties in with the end of NEMESIS. At the end of NEMESIS we saw B4 remembered a song Data had been shown to know at the start of the film. Data had downloaded all his programs into B4. Data had, much earlier, downloaded all of his daughter Lal's programs into himself, and said it gave him access to all her memories. The online source says that eventually Data's memories surfaced in B4, and since B4 had essentially no experiences, Data's consciousness took over. Data then assisted some Starfleet engineers in upgrading B4's less sophisticated brain, so it'd be more like the one Data's programs had originally been running in. Data, according to this "official" source, is now alive and well, living in B4's body, and apparently is viewed by Starfleet as the same person we knew. This is why he was alive in the prequel comic as Captain of Enterprise-E. No, not an onscreen occurence, but apparently counted as legit. Of course, the comic was counted as legit until someone connected to the movie said "Oh no. The comic's not canon." EDIT: As for Brent aging, in the episode where Juliana Soong was introduced, the comment was made that her android body used the same aging program that Data's did, so onscreen we were told to expect to see Data aging, even into the form of an elderly man (eventually).