DakkaDakka Forum
On the whole "limited edition" Grandmaster Edition thing: Andy specifically said on the recent livestream that this is in part because they've never done a box set of this scale before, so they weren't sure how many copies to print. Once they see how well it's selling and how popular it is, they'll be able to print more copies, which means that the GME may be unavailable for a short period during that time.*
He also stated when asked about vehicles and infantry that "many, many years down the line we could possibly expand the game to include these". Take that how you will, but to me it sounds like they*currently*have no plans to expand beyond Titans, but that they may be open to the possibility. I never played the original Epic, so personally I'm more than fine with it just being Titans of various sorts.