I'm curious on which version of the Solo twins we'll get? Heir to the Empire series babies? (probably not) NJO Teenagers? Legacy of the Force Adults?
When asked about this by SSG back in December Hasbro said:
SSG: You said in a recent answer that the Solo twins, while difficult to do because of limited visual references, were high on your wish list. Hypothetically speaking, if you were to make these long-request characters, which versions would you do? Young Jedi Knights (there's a good picture of them in the recent Jedi vs. Sith guide), NJO-era Jedi Knights (probably the most requested versions, and based on Japanese cover art which is probably the largest body of visual reference for these characters and was even used by the Official Site as its EU menu before the redesign) or Legacy of the Force-era (with the added advantage that an alternate head and lightsaber and removable cape would allow you to do Jacen and Caedus as one figure)?
Hasbro: If we did them, hypothetically speaking, it would be the New Jedi Order-era, based on the Japanese cover art. This would be the most solid selection for the exact reasons you have pointed out - prevalence and familiarity with the character images. If we ever did Caedus, it would have to be new sculpt since the NJO-version would not work for a retrofit.