This is an interesting question that I would also like to see answered. My suspicion is that it will probably be capped at 25,000 even in the full game to force you to spend it on things. I dont think there is anything that will cost more than that, so it would make sense for them to cap it at that and force you to either spend it, or collect it for the high level items. There were a lot of items that didnt even use glimmer. Things like Strange Coin, Motes of Light, Vanguard and Crucible marks all serve as currency, so it doesnt look like Glimmer will be used for much.